Therapeutic amounts of intravenous salbutamol (albuterol) in four healthy people were associated with decreased plasma levels of calcium, magnesium, phosphate, and potassium.¹⁵ Decreased potassium levels have been reported with oral,¹⁶ intramuscular, and subcutaneous albuterol administration.¹⁷ How frequently this effect occurs is not known; whether these changes are preventable through diet or supplementation is also unknown.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Aluminum hydroxide may increase urinary and stool loss of calcium.¹⁸ Also, aluminum is a toxic mineral, and a limited amount of aluminum absorption from aluminum-containing antacids does occur.¹⁹ As a result, most doctors do not recommend routine use of aluminum-containing antacids.²⁰ Other types of antacids containing calcium or magnesium instead of aluminum are available.

Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.²¹ Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.²² Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.²³

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

In 205 healthy postmenopausal women, caffeine consumption (three cups of coffee per day) was associated with bone loss in women with calcium intake of less than 800 mg per day.²⁴ In a group of 980 postmenopausal women, lifetime caffeine intake equal to two cups of coffee per day was associated with decreased bone density in those who did not drink at least one glass of milk daily during most of their life.²⁵ However, in 138 healthy postmenopausal women, long-term dietary caffeine (coffee) intake was not associated with bone density.²⁶ Until more is known, postmenopausal women should limit caffeine consumption and consume a total of approximately 1,500 mg of calcium per day (from diet and supplements).

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.²⁸

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.²⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.³⁰

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.³¹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, and K.^{32 , 33} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.³⁴ Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.³⁵

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.³⁶

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.³⁷

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Bile acid sequestrants may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, and K.^{38 , 39} Other medications and vitamin supplements should be taken one hour before or four to six hours after bile acid sequestrants for optimal absorption.⁴⁰ Animal studies suggest calcium and zinc may also be depleted by taking cholestyramine.⁴¹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Bile acid sequestrants, including colestipol, may prevent absorption of folic acid and the fat-soluble vitamins A, D, E, K.^{42 , 43} People taking colestipol should consult with their doctor about vitamin malabsorption and supplementation. People should take other drugs and vitamin supplements one hour before or four to six hours after colestipol to improve absorption.⁴⁴

Animal studies suggest calcium and zinc may be depleted by taking cholestyramine, another bile acid sequestrant. ⁴⁵ Whether these same interactions would occur with colestipol is not known.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Oral corticosteroids reduce absorption of calcium⁴⁶ and interfere with the activation and metabolism of the vitamin,^{47 [REF] 48 , 49} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.⁵⁰ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.⁵¹ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Cycloserine may interfere with calcium and magnesium absorption.⁵² 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.^{53 , 54} The clinical importance of this interaction is unclear.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁵⁵

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Oral corticosteroids reduce absorption of calcium⁶³ and interfere with the activation and metabolism of the vitamin,^{64 , 65 , 66 , 67} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.⁶⁸ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.⁶⁹ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Diclofenac decreases the amount of calcium lost in the urine,⁷⁰ which may help prevent bone loss in postmenopausal women.⁷¹

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁷²

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

A study of felodipine indicated that the drug caused increased excretion of calcium.⁷³ Whether this effect could lead to increased bone loss is unknown, but some health practitioners may recommend calcium supplementation to individuals taking felodipine. Although the effectiveness of some calcium channel blockers may be reduced with calcium supplementation,⁷⁴ this effect has not been observed in people taking felodipine.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁷⁵

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁷⁶

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.⁷⁷ Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Elevated calcium and vitamin D blood levels are commonly found in people with sarcoidosis. In one individual with sarcoidosis, taking flubiprofen lowered elevated blood calcium levels, but did not alter the concentration of vitamin D.⁷⁸ One controlled study showed that flurbiprofen reduced blood levels of vitamin D in people with frequent calcium kidney stones.⁷⁹ Further research is needed to determine whether flurbiprofen reduces blood calcium and vitamin D levels in healthy people.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.⁸⁰ Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Calcium depletion, in some cases severe, has been observed in some people taking loop diuretics.⁸¹ People taking loop diuretics should ask their doctor whether they should take a calcium supplement or have their blood level of calcium monitored.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.⁸² Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches) cramps, and spasm during the first two weeks of life.⁸³ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Gentamicin has been associated with hypocalcemia (low calcium levels) in humans.⁸⁴ In a study using rats, authors reported oral calcium supplementation reduced gentamicin-induced kidney damage.⁸⁵ The implications of this report for humans are unclear. People receiving gentamicin should ask their doctor about monitoring calcium levels and calcium supplementation.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Normally, the active form of vitamin D increases the absorption of calcium into the body. In a 45-year-old woman with sarcoidosis, taking hydroxychloroquine blocked the formation of active vitamin D, which helped normalize elevated blood levels of calcium in this case.⁸⁶ Whether hydroxychloroquine has this effect in people who don’t have sarcoidosis or elevated calcium is unknown. Until controlled research explores this interaction more thoroughly, people taking hydroxychloroquine might consider having their vitamin D and/or calcium status monitored by a health practitioner.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁸⁷

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁸⁸

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Indomethacin has been reported to decrease absorption of folic acid and vitamin C.⁸⁹ Under certain circumstances, indomethacin may interfere with the actions of vitamin C.⁹⁰ Calcium and phosphate levels may also be reduced with indomethacin therapy.⁹¹ It remains unclear whether people taking this drug need to supplement any of these nutrients.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

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.^{92 , 93} Supplementation with vitamin B6 is thought to help prevent isoniazid-induced niacin deficiency; however, small amounts of vitamin B6 (e.g. 10 mg per day) appear to be inadequate in some cases.⁹⁴ People should consider using a daily multivitamin-mineral supplement during isoniazid therapy.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Most of an inhaled dose of beclomethasone is actually swallowed, which may lead to reduced absorption of calcium.⁹⁵ Health practitioners may recommend calcium supplementation to individuals using beclomethasone inhalers.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁹⁶

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁹⁷

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁹⁸

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.⁹⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹⁰⁴

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Mineral oil has interfered with the absorption of many nutrients, including beta-carotene, calcium, phosphorus, potassium, and vitamins A, D, K, and E in some,¹¹² but not all,¹¹³ research. Taking mineral oil on an empty stomach may reduce this interference. It makes sense to take a daily multivitamin-mineral supplement two hours before or after mineral oil. It is important to read labels, because many multivitamins do not contain vitamin K or contain inadequate (less than 100 mcg per day) amounts.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

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.^{114 , 115} 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.

In a study of elderly women, administration of omeprazole decreased the absorption of calcium,¹¹⁶ presumably because the drug decreased the stomach's production of hydrochloric acid, which is necessary for calcium absorption. The form of calcium used in the study to test calcium absorption was calcium carbonate. Drugs that reduce stomach acid secretion may not inhibit other forms of calcium, such as calcium citrate.¹¹⁷

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.¹¹⁸ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches), cramps, and spasms that can be caused by calcium deficiency during the first two weeks of life.¹¹⁹ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.¹²⁰ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.¹²¹ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹²²

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Oral corticosteroids reduce absorption of calcium¹²³ and interfere with the activation and metabolism of the vitamin,^{124 [REF] 125 , 126} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.¹²⁷ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.¹²⁸ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Oral corticosteroids reduce absorption of calcium¹²⁹ and interfere with the activation and metabolism of the vitamin,^{130 , 131 , 132 , 133} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.¹³⁴ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.¹³⁵ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Slight increases in blood calcium levels may occur in people taking sucralfate, which could be aggravated by calcium supplementation.¹³⁶ Therefore, people taking calcium supplements and sucralfate should have their blood calcium levels monitored by their healthcare practitioner and may need to avoid calcium supplementation.

Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.¹³⁷ 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.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹³⁸

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹³⁹

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

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.¹⁴⁰ 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.¹⁴¹ 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.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

A review of the research literature indicates that triamterene may increase calcium loss.¹⁴² The importance of this information is unclear.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.¹⁴³ 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.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹⁴⁴

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹⁴⁵

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

The chemotherapy drug cisplatin may cause kidney damage, resulting in depletion of calcium and phosphate.¹⁴⁶

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Metformin therapy has been shown to deplete vitamin B12,¹⁰⁰ and sometimes, but not always,¹⁰¹ folic acid as well.¹⁰² This depletion occurs through the interruption of a calcium-dependent mechanism. Supplementation with calcium has reversed this effect in a clinical trial.¹⁰³ People taking metformin should supplement vitamin B12 and folic acid or ask their doctor to monitor folic acid and vitamin B12 levels.

Oral corticosteroids reduce absorption of calcium¹⁰⁵ and interfere with the activation and metabolism of the vitamin,^{106 , 107 , 108 , 109} increasing the risk of bone loss. Doctors can measure levels of activated vitamin D (called 1,25 dihydroxycholecalciferol) to determine whether a deficiency exists; if so, activated vitamin D is only available by prescription. A study of rheumatoid arthritis patients treated with low amounts of prednisone found that those who received 1,000 mg of calcium per day plus 500 IU of vitamin D per day for two years experienced no bone loss during that time period.¹¹⁰ An analysis of properly conducted trials concluded that supplementation with vitamin D and calcium was more effective than placebo or calcium alone in protecting against corticosteroid-induced osteoporosis.¹¹¹ Most doctors recommend 1,000 mg of calcium and 400–800 IU vitamin D per day for the prevention of osteoporosis.

Supplementation with 1,500 mg per day of calcium enhances the effects of nasal calcitonin on bone mass of the lumbar spine.²⁷ Women who take a calcitonin nasal product for osteoporosis should also take calcium.

Calcium supplements are known to interfere with the absorption of ciprofloxacin. The same interference has been shown to occur when calcium-fortified orange juice is taken at the same time as ciprofloxacin.¹⁴⁸

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.¹⁴⁹ Therefore, individuals should take tetracyclines at least two hours before or after products containing minerals.

Many minerals can decrease the absorption and reduce effectiveness of doxycycline, including calcium, magnesium, iron, zinc, and others.¹⁵⁰ 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.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

A recent study showed that taking calcium carbonate and gemifloxacin at the same time results in a significant reduction in blood levels of the drug.¹⁵¹ Consequently, gemifloxacin and calcium supplements should not be taken at the same time.

Calcium supplements, if taken at the same time as some beta-blocker drugs, may reduce blood levels of the drug.¹⁵² However, whether calcium affects nadolol in this manner is unknown. Until more information is available, people on nadolol should take calcium supplements an hour before or two hours after the drug.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Minerals including calcium, iron, magnesium, and zinc can bind to fluoroquinolones, including ofloxacin, greatly reducing drug absorption.¹⁵³ 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.¹⁵⁴

One controlled study showed that taking sotalol with a calcium gluconate solution dramatically reduces the absorption of the drug.¹⁵⁵ Consequently, people who take a calcium supplement should take sotalol an hour before or two hours after the calcium.

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.

People with kidney failure may develop high blood levels of calcium while taking calcium acetate. Since calcium acetate is a source of supplemental calcium, people taking the drug should avoid taking additional calcium supplements.¹⁴⁷ People experiencing adverse effects of high blood calcium—such as loss of appetite, mental depression, poor memory, and muscle weakness—should notify their healthcare practitioner.

Calcium supplements may interfere with alendronate absorption.¹⁵⁶ However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.¹⁵⁷ Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.¹⁵⁸ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.¹⁵⁹ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.¹⁶⁰ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.¹⁶¹ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.¹⁶² As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{163 , 164 , 165} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{166 , 167 , 168} OCs may interfere with manganese absorption.¹⁶⁹ The clinical importance of these actions remains unclear.

Thyroid hormones have been reported to increase urinary loss of calcium.¹⁷⁰ However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.^{171 , 172} Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.¹⁷³ For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.¹⁷⁴ Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Erythromycin may interfere with the absorption and/or activity of calcium, folic acid, magnesium, vitamin B6 and vitamin B12,¹⁷⁵ 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.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{176 , 177 , 178} Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{179 , 180 , 181} Oral contraceptives may interfere with manganese absorption.¹⁸² The clinical importance of these actions remains unclear.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

A review of literature suggests that women who use oral contraceptives may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{183 , 184 , 185} Oral contraceptive use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{186 , 187 , 188} Oral contraceptives may interfere with manganese absorption.¹⁸⁹ The clinical importance of these actions remains unclear.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{190 , 191 , 192} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{193 , 194 , 195} OCs may interfere with manganese absorption.¹⁹⁶ The clinical importance of these actions remains unclear.

Calcium supplements may interfere with alendronate absorption.¹⁹⁷ However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.¹⁹⁸ Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.¹⁹⁹ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.²⁰⁰ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁰¹ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁰² As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁰³ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Dairy products are rich in calcium. Lactase-deficient people may not consume milk and therefore have fewer dietary sources of calcium available to them. Lactase products allow lactase-deficient people to digest milk products, increasing their sources and intake of dietary calcium.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.²⁰⁴ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.²⁰⁵ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{206 , 207 , 208} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{209 , 210 , 211} OCs may interfere with manganese absorption.²¹² The clinical importance of these actions remains unclear.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{213 , 214 , 215} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{216 , 217 , 218} OCs may interfere with manganese absorption.²¹⁹ The clinical importance of these actions remains unclear.

Thyroid hormones have been reported to increase urinary loss of calcium.²²⁰ However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.^{221 , 222} Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.²²³ For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.²²⁴ Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

Thyroid hormones have been reported to increase urinary loss of calcium.²²⁵ However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.^{226 , 227} Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.²²⁸ For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.²²⁹ Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Thyroid hormones have been reported to increase urinary loss of calcium.²³⁰ However, recent research suggests that, under most circumstances, taking thyroid hormones may not be associated with reduced bone density.^{231 , 232} Calcium supplementation for people taking long-term thyroid medication has not yet been proven to be either helpful or necessary.

Simultaneous ingestion of some calcium formulations with levothyroxine has been reported to reduce the effectiveness of levothyroxine.²³³ For example, 1,200 mg per day of calcium as calcium carbonate, taken along with levothyroxine, significantly reduced absorption of the thyroid hormone.²³⁴ Levothyroxine activity will not be blocked if it is taken in the morning and calcium carbonate is taken after lunch and dinner. Separating these medications by at least four hours is recommended.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{235 , 236 , 237} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{238 , 239 , 240} OCs may interfere with manganese absorption.²⁴¹ The clinical importance of these actions remains unclear.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁴² As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.1 As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Taking calcium, iron, magnesium, or zinc at the same time as minocycline can decrease the absorption of both the drug^{243 , 244} and the mineral. Therefore, calcium, iron, magnesium, or zinc supplements, if used, should be taken an hour before or after the drug.

A review of literature suggests that women who use OCs may experience decreased vitamin B1, B2, B3, B12, C, and zinc levels.^{245 , 246 , 247} OC use has been associated with increased absorption of calcium and copper and with increased blood levels of copper and vitamin A.^{248 , 249 , 250} OCs may interfere with manganese absorption.²⁵¹ The clinical importance of these actions remains unclear.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.²⁵² Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.²⁵³ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Calcium supplements may interfere with alendronate absorption.²⁵⁴ However, one researcher suggested that addition of large amounts of supplemental calcium to alendronate therapy in patients with bone metastases (with evidence of osteomalacia) related to prostate cancer might improve the clinical outcome.²⁵⁵ Moreover, both calcium and alendronate are commonly used in the treatment of osteoporosis in the same people. To prevent potential interactions, alendronate should be taken two hours before or after calcium supplements.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁵⁶ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.²⁵⁷ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.²⁵⁸ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Short-term treatment with risedronate in people with hyperparathydoidism—a disorder characterized by high blood levels of calcium—resulted in lower calcium blood levels.²⁵⁹ Additional research is needed to determine whether people taking risedronate for Paget’s disease might develop low blood calcium levels. As a precaution, people with Paget’s disease should take supplemental calcium and vitamin D if dietary intake is inadequate. However, taking risedronate at the same time as calcium supplements reduces absorption of the drug.²⁶⁰ Therefore, people taking risedronate for Paget’s disease should take calcium supplements an hour before or two hours after taking the drug.

The interaction is supported by preliminary, weak, fragmentary, and/or contradictory scientific evidence.

Research shows that calcium from leg bones may be transferred to bones in the spine causing stress fractures when fluoride is taken alone. However, supplementing with 1,500 mg of calcium each day together with slow-release forms of fluoride increases the bone density of the lumbar spine without causing fractures.²⁶¹ Therefore, people taking sodium fluoride to treat osteoporosis should probably supplement with calcium to prevent this adverse effect. However, taking fluoride and calcium at the same time significantly reduces the absorption of fluoride;²⁶² consequently, they should be taken at least an hour apart.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.²⁶³ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches, cramps, and spasm) during the first two weeks of life.²⁶⁴ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.

Thiazide diuretics decrease calcium loss in the urine due to actions on the kidneys.²⁶⁵ As a result, it may be less important for some people taking thiazide diuretics to supplement calcium than it is for other people.

Individuals on long-term multiple anticonvulsant therapy may develop below-normal blood levels of calcium, which may be related to drug-induced vitamin D deficiency.²⁶⁶ Two infants born to women taking high doses of phenytoin and phenobarbital while pregnant developed jitteriness and tetany (a syndrome characterized by muscle twitches), cramps, and spasms that can be caused by calcium deficiency during the first two weeks of life.²⁶⁷ Controlled research is needed to determine whether pregnant women who are taking anticonvulsant medications should supplement with additional amounts of calcium and vitamin D.