Magnesium for Sports & Fitness

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Why Use

Magnesium

Why Do Athletes Use It?*

Some athletes say that magnesium helps curb dehydration and prevent muscle cramping.

What Do the Advocates Say?*

People who are doing “heavy-duty” exercise lose a lot of magnesium through urination and sweat, so it’s important that it’s replaced. To keep water in the blood vessels, electrolytes, such as magnesium, need to be replaced. Therefore, to curb dehydration, electrolyte drinks are more effective than plain water.

Magnesium helps to prevent muscle cramping after exercise, too.

*Athletes and fitness advocates may claim benefits for this supplement based on their personal or professional experience. These are individual opinions and testimonials that may or may not be supported by controlled clinical studies or published scientific articles.

Dosage & Side Effects

Magnesium

How Much Is Usually Taken by Athletes?

Magnesium deficiency can reduce exercise performance and contribute to muscle cramps, but sub-optimal intake does not appear to be a problem among most groups of athletes.1 , 2 Controlled trials suggest that magnesium supplementation might improve some aspects of physiology important to sports performance in some athletes,3 , 4 but controlled and double-blind trials focusing on performance benefits of 212 to 500 mg per day of magnesium have been inconsistent.5 , 6 , 7 , 8 , 9 , 10 It is possible that magnesium supplementation benefits only those who are deficient or who are not highly trained athletes. 11 , 12

Side Effects

Comments in this section are limited to effects from taking oral magnesium. Side effects from intravenous use of magnesium are not discussed.

Taking too much magnesium often leads to diarrhea. For some people this can happen with amounts as low as 350–500 mg per day. More serious problems can develop with excessive magnesium intake from magnesium-containing laxatives. However, the amounts of magnesium found in nutritional supplements are unlikely to cause such problems. People with kidney disease should not take magnesium supplements without consulting a doctor.

Interactions with Supplements, Foods, & Other Compounds

Vitamin B6 increases the amount of magnesium that can enter cells. As a result, these two nutrients are often taken together. Magnesium may compete for absorption with other minerals. Taking a multimineral supplement avoids this potential problem.

Interactions with Medicines

Certain medicines interact with this supplement.

Types of interactions: Beneficial Adverse Check

Replenish Depleted Nutrients

  • Albuterol

    Therapeutic amounts of intravenous salbutamol (albuterol) in four healthy people were associated with decreased plasma levels of calcium, magnesium, phosphate, and potassium.13 Decreased potassium levels have been reported with oral,14 intramuscular, and subcutaneous albuterol administration.15 How frequently this effect occurs is not known; whether these changes are preventable through diet or supplementation is also unknown.

  • Amphotericin B

    Amphotericin B has been reported to increase urinary excretion of magnesium.16 It remains unclear whether it is important for people taking this drug to supplement magnesium.

  • Bendroflumethiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,17 although this deficiency may not be reflected by a low blood level of magnesium.18 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.19

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.20 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.21 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.22 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.23

  • Bumetanide

    Potassium-depleting diuretics, including loop diuretics, cause the body to lose potassium. Loop diuretics may also cause cellular magnesium depletion,24 although this deficiency may not be reflected by a low blood level of magnesium.25 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including loop diuretics, should supplement both potassium and magnesium.26

    People taking loop diuretics should be monitored by their doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.27 Fruit is high in potassium, and increasing fruit intake is another way of supplementing potassium. Magnesium supplementation is typically 300–400 mg per day.

  • Busulfan

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.28 , 29 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.30 , 31 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.32 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Capecitabine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.33 , 34 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.35 , 36 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.37 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Carboplatin

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.38 , 39 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.40 , 41 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.42 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Carmustine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.43 , 44 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.45 , 46 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.47 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Chlorambucil

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.48 , 49 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.50 , 51 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.52 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Chlorothiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,53 although this deficiency may not be reflected by a low blood level of magnesium.54 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.55

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.56 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.57 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.58 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.59

  • Chlorthalidone

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,60 although this deficiency may not be reflected by a low blood level of magnesium.61 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.62

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.63 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.64 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.65 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.66

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  • Cisplatin

    Cisplatin may cause excessive loss of magnesium and potassium in the urine.67 , 68 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.69 , 70 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.71 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Cladribine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.72 , 73 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.74 , 75 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.76 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Cycloserine

    Cycloserine may interfere with calcium and magnesium absorption.77 The clinical significance of these interactions is unclear.

    Cycloserine may interfere with the absorption and/or activity of folic acid, vitamin B6, and vitamin B12.78 , 79 The clinical importance of this interaction is unclear.

  • Cyclosporine

    Cyclosporine has been associated with low blood magnesium levels and undesirable side effects.80 , 81 , 82 Some doctors suggest monitoring the level of magnesium in red blood cells, rather than in serum, as the red blood cell test may be more sensitive for evaluating magnesium status.

  • Cytarabine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.83 , 84 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.85 , 86 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.87 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Desogestrel-Ethinyl Estradiol

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.88 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.89 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Dexlansoprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).90 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).91 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.92
  • Docetaxel

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.97 , 98 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.99 , 100 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.101 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

    Glutathione , the main antioxidant found within cells, is frequently depleted in individuals on chemotherapy and/or radiation. Preliminary studies have found that intravenously injected glutathione may decrease some of the adverse effects of chemotherapy and radiation, such as diarrhea.102

  • Docusate

    A woman and her newborn infant experienced low blood levels of magnesium, which was possibly due to chronic use of docusate throughout and after pregnancy.103 Controlled research is necessary to determine whether people taking docusate for long periods of time need to supplement magnesium.

  • Erlotinib

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.104 , 105 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.106 , 107 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.108 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Erythromycin

    Erythromycin may interfere with the absorption and/or activity of calcium, folic acid, magnesium, vitamin B6 and vitamin B12,109 which may cause problems, especially with long-term erythromycin treatment. Until more is known, it makes sense for people taking erythromycin for longer than two weeks to supplement with a daily multivitamin-multimineral.

  • Esomeprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).110 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).111 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.112
  • Esomeprazole Magnesium
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).113 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).114 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.115
  • Ethinyl Estradiol and Levonorgestrel

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.116 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.117 Although the importance of this interaction remains somewhat unclear, supplementation with 250 to 350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Ethinyl Estradiol and Norethindrone

    Women using OCs were found to have significantly lower serum magnesium levels in a controlled study.118 In a preliminary study, blood levels of magnesium decreased in women taking an OC containing ethinyl estradiol and levonorgestrel.119 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Ethinyl Estradiol and Norgestimate

    Women using OCs were found to have significantly lower serum magnesium levels in a controlled study.120 In a preliminary study, blood levels of magnesium decreased in women taking an OC containing ethinyl estradiol and levonorgestrel.121 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Ethinyl Estradiol and Norgestrel

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.122 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.123 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Etoposide

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.124 , 125 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.126 , 127 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.128 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Felodipine

    Increased magnesium excretion has been observed in studies of individuals taking felodipine.129 Therefore, some physicians may recommend magnesium supplementation to their patients taking felodipine.

  • Floxuridine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.131 , 132 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.133 , 134 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.135 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Fludarabine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.136 , 137 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.138 , 139 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.140 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Furosemide

    Potassium-depleting diuretics, including loop diuretics, cause the body to lose potassium. Loop diuretics may also cause cellular magnesium depletion,141 although this deficiency may not be reflected by a low blood level of magnesium.142 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including loop diuretics, should supplement both potassium and magnesium.143

    People taking loop diuretics should be monitored by their doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.144 Fruit is high in potassium, and increasing fruit intake is another way of supplementing potassium. Magnesium supplementation is typically 300–400 mg per day.

  • Gentamicin

    Gentamicin has been associated with urinary loss of magnesium, resulting in hypomagnesemia (low magnesium levels) in humans.145 , 146

  • Hydrochlorothiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,148 although this deficiency may not be reflected by a low blood level of magnesium.149 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.150

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.151 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.152 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.153 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.154

  • Hydroflumethiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,155 although this deficiency may not be reflected by a low blood level of magnesium.156 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.157

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.158 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.159 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.160 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.161

  • Hydroxyurea

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.162 , 163 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.164 , 165 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.166 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Ifosfamide

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.167 , 168 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.169 , 170 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.171 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Indapamide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,172 although this deficiency may not be reflected by a low blood level of magnesium.173 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.174

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.175 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.176 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.177 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.178

  • Irinotecan

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.179 , 180 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.181 , 182 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.183 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Isoniazid

    Isoniazid may interfere with the activity of other nutrients, including vitamin B3 (niacin), vitamin B12, vitamin D, and vitamin E, folic acid, calcium, and magnesium.184 , 185People should consider using a daily multivitamin-mineral supplement during isoniazid therapy.

  • Lansoprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).186 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).187 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.188
  • Levonorgestrel

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.189 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.190 Although the importance of this interaction remains somewhat unclear, supplementation with 250 to 350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Levonorgestrel-Ethinyl Estrad

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.191 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.192 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Lomustine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.193 , 194 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.195 , 196 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.197 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Mechlorethamine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.198 , 199 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.200 , 201 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.202 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Melphalan

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.203 , 204 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.205 , 206 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.207 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Mercaptopurine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.208 , 209 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.210 , 211 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.212 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

    Many chemotherapy drugs can cause diarrhea, lack of appetite, vomiting, and damage to the gastrointestinal tract. Recent anti-nausea prescription medications are often effective. Nonetheless, nutritional deficiencies still occur.213 People undergoing chemotherapy should talk to their doctor about whether supplementing with a multivitamin-mineral will protect them against deficiencies.

  • Mestranol and Norethindrone

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.214 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.215 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Methotrexate

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.216 , 217 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.218 , 219 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.220 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Methyclothiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,221 although this deficiency may not be reflected by a low blood level of magnesium.222 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.223

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.224 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.225 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.226 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.227

  • Metolazone

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,3 although this deficiency may not be reflected by a low blood level of magnesium.4 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.5

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.6 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.7 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.8 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.9

  • Neomycin

    Neomycin can decrease absorption or increase elimination of many nutrients, including calcium, carbohydrates, beta-carotene, fats, folic acid, iron, magnesium, potassium, sodium, and vitamin A, vitamin B12, vitamin D, and vitamin K.228 , 229 Surgery preparation with oral neomycin is unlikely to lead to deficiencies. It makes sense for people taking neomycin for more than a few days to also take a multivitamin-mineral supplement.

  • Norgestimate-Ethinyl Estradiol

    Women using oral contraceptives were found to have significantly lower serum magnesium levels in a controlled study.230 In a preliminary study, blood levels of magnesium decreased in women taking an oral contraceptive containing ethinyl estradiol and levonorgestrel.231 Although the importance of this interaction remains somewhat unclear, supplementation with 250–350 mg of magnesium per day is a safe and reasonable supplemental level for most adults.

  • Pantoprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).234 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).235 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.236
  • Polifeprosan 20 with Carmustine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.237 , 238 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.239 , 240 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.241 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Polythiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,242 although this deficiency may not be reflected by a low blood level of magnesium.243 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.244

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.245 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.246 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.247 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.248

  • Rabeprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).250 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).251 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.252
  • Sulfamethoxazole

    Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.255 This is generally not a problem when taking sulfamethoxazole for two weeks or less. People taking sulfamethoxazole for longer than two weeks should ask their doctor about nutrient monitoring and supplementation.

    Note: Since sulfamethoxazole is often prescribed in combination with trimethoprim (for example, in Bactrim or Septra), it may be easy to associate this interaction with trimethoprim. However, this interaction is not known to occur with trimethoprim alone.

  • Theophylline

    Preliminary evidence indicates that theophylline can promote potassium and magnesium deficiency.256 , 257 Some doctors have noted a tendency for persons on theophylline to become deficient in these minerals. Therefore, supplementing with these minerals may be necessary during theophylline therapy. Consult with a doctor to make this determination.

  • Thioguanine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.258 , 259 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.260 , 261 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.262 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Thiotepa

    Cisplatin may cause excessive loss of magnesium and potassium in the urine.263 , 264 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.265 , 266 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.267 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Tobramycin

    Calcium , magnesium, and potassium depletion requiring prolonged replacement were reported in a child with tetany who had just completed a three-week course of i.v. tobramycin.268 The authors suggest this may have been due to kidney damage related to the drug. Seventeen patients with cancer developed calcium, magnesium, and potassium depletion after treatment with aminoglycoside antibiotics, including tobramycin.269 The authors suggested a possible potentiating action of tobramycin-induced mineral depletion by chemotherapy drugs, especially doxorubicin (Adriamycin®).

    Until more is known, people receiving i.v. tobramycin should ask their doctor about monitoring calcium, magnesium, and potassium levels and the possibility of mineral replacement.

  • Torsemide

    Potassium-depleting diuretics, including loop diuretics, cause the body to lose potassium. Loop diuretics may also cause cellular magnesium depletion,270 although this deficiency may not be reflected by a low blood level of magnesium.271 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including loop diuretics, should supplement both potassium and magnesium.272

    People taking loop diuretics should be monitored by their doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.273 Fruit is high in potassium, and increasing fruit intake is another way of supplementing potassium. Magnesium supplementation is typically 300–400 mg per day.

  • Trichlormethiazide

    Potassium-depleting diuretics, including thiazide diuretics, cause the body to lose potassium; they may also cause cellular magnesium depletion,274 although this deficiency may not be reflected by a low blood level of magnesium.275 Magnesium loss induced by potassium-depleting diuretics can cause additional potassium loss. Until more is known, it has been suggested that people taking potassium-depleting diuretics, including thiazide diuretics, should supplement both potassium and magnesium.276

    People taking thiazide diuretics should be monitored by their prescribing doctor, who will prescribe potassium supplements if needed. Such supplementation is particularly critical before surgery in patients with a history of heart disease. In a preliminary study, people with low blood levels of potassium (in part related to diuretic use) had a higher incidence of serious problems resulting from surgery (including death) compared with those having normal potassium levels.277 A double-blind trial showed that thiazide diuretic use led to a reduction in blood levels of potassium in some participants. Those experiencing decreased potassium levels were also more likely to experience cardiovascular events, such as heart attacks, stroke, heart failure, aneurysm, and sudden cardiac death.278 Fruit is high in potassium, and increasing fruit intake (especially bananas) is another way of supplementing potassium.

    Magnesium supplementation for people taking thiazide diuretics is typically 300–600 mg per day, though higher amounts (over 800 mg per day) have been reported in a controlled study to reduce side effects of thiazides.279 Combining supplementation of both potassium and magnesium has been reported to correct abnormally low blood levels of potassium and also to protect against excessive loss of magnesium.280

  • Trimethoprim/ Sulfamethoxazole

    Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.281 This is generally not a problem when taking sulfamethoxazole for two weeks or less. People taking sulfamethoxazole for longer than two weeks should ask their doctor about nutrient monitoring and supplementation.

  • Uracil Mustard

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.282 , 283 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.284 , 285 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.286 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Vinblastine

    The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.287

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.288 , 289 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.290 , 291 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.292 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

  • Vincristine

    The chemotherapy drug cisplatin may cause excessive loss of magnesium and potassium in the urine.293 , 294 Preliminary reports suggest that both potassium and magnesium supplementation may be necessary to increase low potassium levels.295 , 296 Severe magnesium deficiency caused by cisplatin therapy has been reported to result in seizures.297 Severe magnesium deficiency is a potentially dangerous medical condition that should only be treated by a doctor. People receiving cisplatin chemotherapy should ask their prescribing doctor to closely monitor magnesium and potassium status.

    Many chemotherapy drugs can cause diarrhea, lack of appetite, vomiting, and damage to the gastrointestinal tract. Recent anti-nausea prescription medications are often effective. Nonetheless, nutritional deficiencies still occur.298 People undergoing chemotherapy should talk to their doctor about whether supplementing with a multivitamin-mineral will protect them against deficiencies.

Reduce Side Effects

  • Oxaliplatin
    In a double-blind trial, intravenous administration of calcium and magnesium before and after administration of oxaliplatin prevented the development of oxaliplatin-induced nerve damage.232 However, in another double-blind trial, the same treatment regimen as in the other study did not prevent oxaliplatin-induced nerve damage.233 It is not known whether oral administration of these minerals would also be beneficial.
  • Quinidine

    People taking potassium-depleting diuretics may develop low potassium and magnesium blood levels. Prolonged diarrhea and vomiting might also result in low blood potassium levels. People with low potassium or magnesium blood levels who take quinidine might develop serious drug side effects.249 Therefore, people taking quinidine should have their blood potassium and magnesium levels checked regularly and might need to supplement with both minerals, especially when taking potassium-depleting diuretics.

  • Sotalol

    Two individuals taking sotalol developed a side effect of the drug (a heart arrhythmia known as torsades de pointes) which was effectively treated with intravenous magnesium.253 , 254 Additional research is needed to determine whether people taking sotalol might be able to prevent this side effect by taking supplemental magnesium.

Support Medicine

  • Digoxin

    People needing digoxin may have low levels of potassium or magnesium,93 increasing the risk for digoxin toxicity. Digoxin therapy may increase magnesium elimination from the body.94 People taking digoxin may benefit from magnesium supplementation.95 Medical doctors do not commonly check magnesium status, and when they do, they typically use an insensitive indicator of magnesium status (serum or plasma levels). The red blood cell magnesium level may be a more sensitive indicator of magnesium status, although evidence is conflicting. It has been suggested that 300–500 mg of magnesium per day is a reasonable amount to supplement.96

  • Fentanyl

    One double-blind study showed that giving magnesium intravenously before surgery dramatically reduced the amount of fentanyl needed to control pain during and after an operation.130 Further research is needed to determine whether people using fentanyl patches might benefit from supplementing with oral magnesium.

  • Glimepiride

    Supplementing magnesium may enhance the blood-sugar-lowering effects of sulfonylurea drugs.147 Though no current studies have investigated whether glimepiride increases the risk of developing hypoglycemia, individuals should closely monitor their blood glucose while taking glimepiride together with magnesium supplements.

Reduces Effectiveness

  • Atorvastatin

    A magnesium- and aluminum-containing antacid was reported to interfere with atorvastatin absorption.300 People can avoid this interaction by taking atorvastatin two hours before or after any aluminum/magnesium-containing antacids. Some magnesium supplements such as magnesium hydroxide are also antacids.

  • Azithromycin

    A magnesium- and aluminum-containing antacid was reported to interfere with azithromycin absorption in a study of ten healthy people.301 People can avoid this interaction by taking azithromycin two hours before or after any aluminum/magnesium-containing products. It has not yet been shown that magnesium compounds typically found in supplements affect absorption of this drug.

  • Cimetidine

    In healthy volunteers, a magnesium hydroxide/aluminum hydroxide antacid, taken with cimetidine, decreased cimetidine absorption by 20 to 25%.303 People can avoid this interaction by taking cimetidine two hours before or after any aluminum/magnesium-containing antacids, including magnesium hydroxide found in some vitamin/mineral supplements. However, the available studies do not clearly indicate if magnesium hydroxide was the problem and may not need to be avoided.

  • Ciprofloxacin

    Minerals such as aluminum, calcium, copper, iron, magnesium, manganese, and zinc can bind to ciprofloxacin, greatly reducing the absorption of the drug.304 , 305 , 306 , 307 Because of the mineral content, people are advised to take ciprofloxacin two hours after consuming dairy products (milk, cheese, yogurt, ice cream, and others), antacids (Maalox®, Mylanta®, Tums®, Rolaids®, and others), and mineral-containing supplements.308

  • Demeclocycline

    Taking mineral supplements or antacids that contain aluminum, calcium, iron, magnesium, or zinc at the same time as tetracyclines inhibits the absorption of the drug.309 Therefore, individuals should take tetracyclines at least two hours before or after products containing minerals.

  • Doxycycline

    Many minerals can decrease the absorption and reduce effectiveness of doxycycline, including calcium, magnesium, iron, zinc, and others.312 To avoid these interactions, doxycycline should be taken two hours before or two hours after dairy products (high in calcium) and mineral-containing antacids or supplements.

  • Famotidine

    In healthy people, a magnesium hydroxide/aluminum hydroxide antacid, taken with famotidine, decreased famotidine absorption by 20–25%.313 People can avoid this interaction by taking famotidine two hours before or after any aluminum/magnesium-containing antacids. Some magnesium supplements such as magnesium hydroxide are also antacids.

  • Folic Acid

    One controlled study showed that taking folic acid together with an antacid containing aluminum and magnesium hydroxide reduced the absorption of the vitamin.314 Therefore, individuals should take folic acid one hour before or two hours after taking antacids containing aluminum and magnesium hydroxide.

  • Gemifloxacin

    One study showed that taking an antacid containing magnesium and aluminum ten minutes before gemifloxacin results in an 85% reduction in the absorption of the drug.315 Consequently, gemifloxacin and supplements containing magnesium should not be taken at the same time.

  • Hydroxychloroquine

    Magnesium supplementation may reduce blood levels of chloroquine, a compound similar to hydroxychloroquine, and decrease its effectiveness.316 Until more is known, people taking hydroxychloroquine for arthritis who are also using magnesium supplements and are not experiencing relief might try avoiding the supplements or taking them at separate times.

  • Levofloxacin

    Taking magnesium supplements at the same time as levofloxacin can reduce the intestinal absorption—and thus the effectiveness—of the drug.317 Consequently, nutritional supplements or antacids containing magnesium, if used, should be taken two hours before or after taking levofloxacin.

  • Minocycline

    Taking calcium, iron, magnesium, or zinc at the same time as minocycline can decrease the absorption of both the drug318 , 319 and the mineral. Therefore, calcium, iron, magnesium, or zinc supplements, if used, should be taken an hour before or after the drug.

  • Nitrofurantoin

    In six healthy men, nitrofurantoin absorption was reduced by also taking magnesium trisilicate.321 Another magnesium compound, magnesium oxide (commonly found in supplements) was shown to bind with nitrofurantoin in a test tube.322

    In a study of 11 people, the rate of nitrofurantoin absorption was delayed despite the fact that the amount of nitrofurantoin ultimately absorbed remained the same when the drug was administered in a colloidal magnesium aluminum silicate suspension.323 It remains unclear whether this interaction is clinically important or if typical magnesium supplements would have the same effect.

  • Nizatidine

    In healthy people, a magnesium hydroxide/aluminum hydroxide antacid, taken with nizatidine, decreased nizatidine absorption by 12%.324 People can avoid this interaction by taking nizatidine two hours before or after any aluminum/magnesium-containing antacids. Some magnesium supplements such as magnesium hydroxide are also antacids.

  • Ofloxacin

    Minerals including calcium, iron, magnesium, and zinc can bind to fluoroquinolones, including ofloxacin, greatly reducing drug absorption.325 Ofloxacin should be taken four hours before or two hours after consuming antacids (Maalox®, Mylanta®, Tumms®, Rolaids® and others) that may contain these minerals and mineral-containing supplements.326

  • Tetracycline

    Many minerals can decrease the absorption of tetracycline, thus reducing its effectiveness. These minerals include aluminum (in antacids), calcium (in antacids, dairy products, and supplements), magnesium (in antacids and supplements), iron (in food and supplements), zinc (in food and supplements), and others.

  • Warfarin

    Iron , magnesium, and zinc may bind with warfarin, potentially decreasing their absorption and activity.329 People on warfarin therapy should take warfarin and iron/magnesium/zinc-containing products at least two hours apart.

Potential Negative Interaction

  • Amiloride

    Preliminary research in animals suggests that amiloride may reduce the urinary excretion of magnesium.299 It is unknown if this same effect would occur in humans. Nevertheless, persons taking more than 300 mg of magnesium per day and amiloride should consult with a doctor, as this combination may lead to potentially dangerous elevations in levels of magnesium in the body. The combination of amiloride and hydrochlorothiazide would likely eliminate this problem, as hydrochlorothiazide may deplete magnesium.

  • Calcium Acetate

    Calcium-containing antacids, when taken together with calcium acetate, may result in abnormally high blood levels of calcium.302 Consequently, people taking calcium acetate should avoid taking calcium-containing antacids.

  • Dexamethasone

    Corticosteroids may increase the body’s loss of magnesium.310 Some doctors recommend that people taking corticosteroids for more than two weeks supplement with 300–400 mg of magnesium per day. Magnesium has also been reported to interfere with the absorption of dexamethasone.311

  • Misoprostol

    A common side effect of misoprostol is diarrhea, which is aggravated by taking magnesium.320 Consequently, individuals who experience diarrhea while taking misoprostol should avoid magnesium supplementation.

  • Spironolactone

    Preliminary research in animals suggests that amiloride, a drug similar to spironolactone, may inhibit the urinary excretion of magnesium.327 It is unknown if this same effect would occur in humans or with spironolactone. Persons taking more than 300 mg of magnesium per day and spironolactone should consult with a doctor as this combination may lead to potentially dangerous increases in the level of magnesium in the body. The combination of spironolactone and hydrochlorothiazide would likely eliminate this problem, as hydrochlorothiazide may deplete magnesium.

  • Triamterene

    Preliminary research in animals suggests that triamterene may inhibit the urinary excretion of magnesium.328 It is unknown if this same effect would occur in humans. Persons taking more than 300 mg of magnesium per day and triamterene should consult with a doctor as this combination may lead to potentially dangerous increases in the level of magnesium in the body. The combination of triamterene and hydrochlorothiazide would likely eliminate this problem, as hydrochlorothiazide may deplete magnesium.

Explanation Required

  • Alendronate

    Absorption of tiludronate, a drug related to alendronate, is reduced when taken with magnesium and/or aluminum-containing antacids.330 This interaction has not yet been reported with alendronate. Until more is known, alendronate should be taken two hours before or after magnesium and/or aluminum-containing antacids.

  • Cortisone

    Corticosteroids may increase the body’s loss of magnesium.331 Some doctors recommend that people taking corticosteroids for more than two weeks supplement with 300–400 mg of magnesium per day. Magnesium has also been reported to interfere with the absorption of dexamethasone.332

  • Epinephrine

    Intravenous administration of epinephrine to human volunteers reduced plasma concentrations of vitamin C.333 Epinephrine and other “stress hormones” may reduce intracellular concentrations of potassium and magnesium.334 Although there are no clinical studies in humans, it seems reasonable that individuals using epinephrine should consume a diet high in vitamin C, potassium, and magnesium, or should consider supplementing with these nutrients.

  • Etidronate

    Absorption of tiludronate, a drug related to alendronate, is reduced when taken with magnesium and/or aluminum-containing antacids.335 This interaction has not yet been reported with alendronate. Until more is known, alendronate should be taken two hours before or after magnesium and/or aluminum-containing antacids.

  • Glipizide

    In a study of people with poorly controlled type 2 diabetes and low blood levels of magnesium, treatment with glipizide was associated with a significant rise in magnesium levels.336 In a randomized trial with eight healthy people, 850 mg magnesium hydroxide increased glipizide absorption and activity.337 In theory, such changes could be therapeutic or detrimental under varying circumstances. Therefore, people taking glipizide should consult with their doctor before taking magnesium supplements.

  • Medroxyprogesterone

    In a group of 37 postmenopausal women treated with conjugated estrogens and medroxyprogesterone for 12 months, urinary zinc and magnesium loss was reduced in those women who began the study with signs of osteoporosis and elevated zinc and magnesium excretion.338 The clinical significance of this interaction remains unclear.

  • Metformin

    In a study of patients with poorly controlled type 2 diabetes, low blood levels of magnesium, and high urine magnesium loss, metformin therapy was associated with reduced urinary magnesium losses but no change in low blood levels of magnesium.339 Whether this interaction has clinical importance remains unclear.

  • Methylprednisolone

    Corticosteroids may increase the body’s loss of magnesium.340 Some doctors recommend that people taking corticosteroids for more than two weeks supplement with 300–400 mg of magnesium per day. Magnesium has also been reported to interfere with the absorption of dexamethasone.341

  • Omeprazole
    In a case report, a man developed severe magnesium deficiency after long-term treatment with a proton pump inhibitor (pantoprazole or lansoprazole).342 Severe magnesium deficiency as a result of the use of proton pump inhibitors appears to be rare among people who have no other risk factors for magnesium deficiency. However, in a study of hospitalized patients, the prevalence of low serum magnesium levels was significantly greater among users of proton pump inhibitors than among nonusers (23% vs. 11%).343 People taking proton pump inhibitors (PPIs) should ask their doctor whether to take a magnesium supplement or whether to have their magnesium levels monitored.344
  • Pamidronate

    Absorption of tiludronate, a drug related to alendronate, is reduced when taken with magnesium and/or aluminum-containing antacids.345 This interaction has not yet been reported with alendronate. Until more is known, alendronate should be taken two hours before or after magnesium and/or aluminum-containing antacids.

  • Prednisolone

    Corticosteroids may increase the body’s loss of magnesium.346 Some doctors recommend that people taking corticosteroids for more than two weeks supplement with 300 to 400 mg of magnesium per day. Magnesium has also been reported to interfere with the absorption of dexamethasone.347

  • Prednisone

    Corticosteroids may increase the body’s loss of magnesium.348 Some doctors recommend that people taking corticosteroids for more than two weeks supplement with 300–400 mg of magnesium per day. Magnesium has also been reported to interfere with the absorption of dexamethasone.349

  • Risedronate

    Taking risedronate at the same time as iron, zinc, or magnesium may reduce the amount of drug absorbed.350 Therefore, people taking risedronate who wish to supplement with these minerals should take them an hour before or two hours after the drug.

  • Troleandomycin

    A magnesium- and aluminum-containing antacid was reported to interfere with absorption of azithromycin, another macrolide drug, in a study of ten healthy people.351 People can avoid this interaction by taking azithromycin two hours before or after any aluminum/magnesium-containing products. It has not yet been shown that magnesium compounds typically found in supplements affect absorption of azithromycin or other similar drugs.

More Resources

Magnesium

Where to Find It

Nuts and grains are good sources of magnesium. Beans, dark green vegetables, fish, and meat also contain significant amounts.

Resources

See a list of books, periodicals, and other resources for this and related topics.