Health Encyclopedia > Drug Interaction by Drug Name > Trimethoprim/Sulfamethoxazole

Trimethoprim/Sulfamethoxazole

Brand Name: Bactrim®, Co-Trimoxazole, Cotrim®, Septra®, SMX/TMP, TMP/SMX, Uroplus®

Trimethoprim/Sulfamethoxazole Information

The antibiotic combination of trimethoprim and sulfamethoxazole (TMP/SMX) is used to treat a wide variety of bacterial infections and some infections due to parasites. Bactrim®, Cotrim®, and Septra® are brand names for products containing identical amounts of TMP/SMX. Bactrim® DS and Septra® DS contain twice as much TMP and SMX as Bactrim® and Septra®.

Summary of Interactions with Vitamins, Herbs, and Foods
(for details about the summarized interactions, read the full article)

May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	Folic acid* Vitamin K*
May be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication.	Bifidobacterium longum* Lactobacillus acidophilus* Lactobacillus casei* Saccharomyces boulardii* Saccharomyces cerevisiae* Vitamin K*
May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.	Saccharomyces boulardii*
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	PABA* Potassium
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.

Trimethoprim/Sulfamethoxazole Interactions with Dietary Supplements

Folic acid
TMP/SMX has, on rare occasions, been associated with anemia due to folic acid deficiency.¹ This effect may be due to trimethoprim.² TMP/SMX should be used with caution in patients with folic acid deficiency, for which a blood test is available. Folic acid replacement does not interfere with the antibacterial activity of TMP/SMX.³ People with AIDS-related pneumonia given TMP/SMX had a worse survival rate when folinic acid, an activated form of folic acid, was added.⁴

PABA (para-aminobenzoic acid)
PABA may interfere with the action of sulfamethoxazole. It should not be taken together with trimethoprim/sulfamethoxazole.

Potassium
TMP/SMX has been reported to increase blood potassium to levels above the normal range in some patients, particularly those with impaired kidney function.⁵ People who have been prescribed TMP/SMX should ask their doctor whether they should avoid potassium supplements, potassium-containing salt substitutes (No Salt®, Morton Salt Substitute®, and others), and 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.⁶

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 boulardii⁷ or Saccharomyces cerevisiae (baker’s or brewer’s yeast)⁸ —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.⁹ 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.¹⁰

Vitamin K
Several cases of excessive bleeding have been reported in people who take antibiotics.¹¹ ¹² ¹³ ¹⁴ 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.¹⁵ Several antibiotics appear to exert a strong effect on vitamin K ac

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Medication Reviews & Side Effects for Trimethoprim/Sulfamethoxazole

Write an online review of Trimethoprim/Sulfamethoxazole

Review Date: 7/7/2007
Medication: Trimethoprim/Sulfamethoxazole -

- Stay Far Away
Medication Type: Generic
Length Taken: Less than 1 month
Strength: 160 mg. X 10 times per day
Side Effects: Gave Me A Rash, Gave Me Blotchy Skin, Loss of Sleep
Other Products Taken:

I was prescribed this medication for a bacterial infection on my feet, which had been itchy, and I scratched them too much. This medication seemed to improve the condition of my feet. However, about the time of the last dose, (28 pills) I turned red all over. This was unusual for me. Then I was very hot. Then I had a very itchy rash all over my body. I was unable to sleep, but of course, it was a weekend, and I didn't want to call the doctor until a weekday, to avoid excessive charges. I applied mud packs on my skin, and eventually my skin cleared up. My dermatologist and the pharmacist confirmed that I had had an allergic reaction. I don't want to take this medication again.

Janet
San Diego, CA

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The information presented in Healthnotes 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. The "reviews" listed for any medical condition, prescription drug, condition or symtpom is provided specifically from eVitamins and is not associated with healthnotes.

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