Sulfamethoxazole

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Also indexed as:

Gantanol

Sulfamethoxazole is a member of the sulfonamide family of antibiotics. It is used for people with infections caused by a variety of bacteria and protozoa. The combination drug product trimethoprim/sulfamethoxazole (TMP/SMX) is used to treat a wide variety of bacterial infections and some infections due to parasites.

Herbs

Summary of Interactions for Sulfamethoxazole

Depletion or interference	Calcium* Folic acid* Magnesium* Vitamin B12* Vitamin B6* Vitamin K*
Adverse interaction	PABA* Potassium
Side effect reduction/prevention	Bifidobacterium longum* Lactobacillus acidophilus* Lactobacillus casei* Saccharomyces boulardii* Saccharomyces cerevisiae* Vitamin K*
Supportive interaction	Saccharomyces boulardii*
Reduced drug absorption/bioavailability	None known

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Supplements

Calcium, Magnesium, Vitamin B12

Sulfonamides, including sulfamethoxazole, can decrease absorption of calcium, magnesium, and vitamin B12.¹ 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.

Folic acid, Vitamin B6, Vitamin K

Sulfonamides, including sulfamethoxazole, can interfere with the activity of folic acid, vitamin B6, and vitamin K.² 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.

PABA (para-aminobenzoic acid)

PABA may interfere with the activity of sulfamethoxazole. PABA should not be taken with this drug until more is known.

Potassium

TMP/SMX has been reported to elevate potassium and other constituents of blood (creatinine and BUN).³ In particular, people with impaired kidney function should be closely monitored by their prescribing doctor for these changes. People taking sulfamethoxazole or TMP/SMX should talk with their prescribing doctor before taking any potassium supplements or potassium-containing products, such as No Salt®, Salt Substitute®, Lite Salt®, and even high-potassium foods (primarily fruit).

Probiotics

A common side effect of antibiotics is diarrhea, which may be caused by the elimination of beneficial bacteria normally found in the colon. Controlled studies have shown that taking probiotic microorganisms-such as Lactobacillus casei, Lactobacillus acidophilus, Bifidobacterium longum, or Saccharomyces boulardii -helps prevent antibiotic-induced diarrhea.⁴

The diarrhea experienced by some people who take antibiotics also might be due to an overgrowth of the bacterium Clostridium difficile, which causes a disease known as pseudomembranous colitis. Controlled studies have shown that supplementation with harmless yeast-such as Saccharomyces boulardii ⁵ or Saccharomyces cerevisiae (baker's or brewer's yeast)⁶ -helps prevent recurrence of this infection. In one study, taking 500 mg of Saccharomyces boulardii twice daily enhanced the effectiveness of the antibiotic vancomycin in preventing recurrent clostridium infection.⁷ Therefore, people taking antibiotics who later develop diarrhea might benefit from supplementing with saccharomyces organisms.

Treatment with antibiotics also commonly leads to an overgrowth of yeast (Candida albicans) in the vagina (candida vaginitis) and the intestines (sometimes referred to as "dysbiosis"). Controlled studies have shown that Lactobacillus acidophilus might prevent candida vaginitis.⁸

Vitamin K

Several cases of excessive bleeding have been reported in people who take antibiotics.^{9, 10, 11, 12} This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal.¹³ Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

Other Interactions

Food

Food may interfere with the absorption of sulfonamides, including sulfamethoxazole. It is best to take sulfamethoxazole on an empty stomach with a full glass of water.^{14, 15}

References

1. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 248-49, 250-1.
2. Holt GA. Food & Drug Interactions. Chicago: Precept Press,1998, 248-49, 251-2.
3. Alappan R, Perazella MA, Buller GK. Hyperkalemia in hospitalized patients treated with trimethoprim-sulfamethoxazole. Ann Intern Med 1996;124:316-20.
4. Elmer GW, Surawicz CM, McFarland LV. Biotherapeutic agents. A neglected modality for the treatment and prevention of selected intestinal and vaginal infections. JAMA 1996;275:870-6 [review].
5. Elmer GW, Surawicz CM, McFarland LV. Biotherapeutic agents. A neglected modality for the treatment and prevention of selected intestinal and vaginal infections. JAMA 1996;275:870-6 [review].
6. Schellenberg D, Bonington A, Champion CM, et al. Treatment of Clostridium difficile diarrhoea with brewer's yeast. Lancet 1994;343:171-2.
7. Surawicz CM, Elmer GW, Speelman P, et al. Prevention of antibiotic-associated diarrhea by Saccharomyces boulardii: A prospective study. Gastroenterol 1989;96:981-8.
8. Elmer GW, Surawicz CM, McFarland LV. Biotherapeutic agents. A neglected modality for the treatment and prevention of selected intestinal and vaginal infections. JAMA 1996;275:870-6 [review].
9. Suzuki K, Fukushima T, Meguro K, et al. Intracranial hemorrhage in an infant owing to vitamin K deficiency despite prophylaxis. Childs Nerv Syst 1999;15:292-4.
10. Huilgol VR, Markus SL, Vakil NB. Antibiotic-induced iatrogenic hemobilia. Am J Gastroenterol 1997;92:706-7.
11. Bandrowsky T, Vorono AA, Borris TJ, Marcantoni HW. Amoxicllin-related postextraction bleeding in an anticoagulated patient with tranexamic acid rinses. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82:610-2.
12. Kaiser CW, McAuliffe JD, Barth RJ, Lynch JA. Hypoprothrombinemia and hemorrhage in a surgical patient treated with cefotetan. Arch Surg 1991;126:524-5.
13. Conly J, Stein K. Reduction of vitamin K2 concentration in human liver associated with the use of broad spectrum antimicrobials. Clin Invest Med 1994;17:531-9.
14. Threlkeld DS, ed. Anti-Infectives, Sulfonamides. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Sep 1997, 364.
15. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 249.

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Last Review: 01-21-2009

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires February 2010.

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