Trimethoprim: Uses, Side Effects, and Drug Interactions

Brand names: Sulfamethoxazole and Trimethoprim

# Overview of Trimethoprim Trimethoprim is an antibiotic medication used to treat bacterial infections, most commonly urinary tract infections. It works by stopping bacteria from growing and multiplying in your body. Doctors may prescribe it by itself or combined with another antibiotic called sulfamethoxazole. This medicine comes in tablet form and is taken by mouth, usually a few times per day depending on the infection being treated and what your doctor recommends. There are several important safety things to know before taking trimethoprim. Tell your doctor about all other medications you take, since trimethoprim can interact with certain drugs and affect how they work in your body. This is especially important if you're taking water pills (diuretics) or other medicines. Older adults need to be extra careful with this combination. Like all antibiotics, trimethoprim can cause side effects in some people, so contact your doctor if you experience any unusual symptoms while taking it. Don't take this medicine if you're allergic to it, and always take it exactly as your doctor prescribes, even if you start feeling better before finishing the full course.

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Most Reported Side Effects (FAERS)

  • PYREXIA6,766 reports
  • OFF LABEL USE6,008 reports
  • FATIGUE5,763 reports
  • NAUSEA5,506 reports
  • DIARRHOEA5,504 reports
  • RASH4,886 reports
  • DYSPNOEA4,870 reports
  • PAIN4,470 reports
  • VOMITING4,314 reports
  • DRUG INEFFECTIVE4,164 reports

Source: FDA Adverse Event Reporting System (FAERS). Voluntary reports do not establish causation.

Recent Recalls (5)

Source: FDA (openFDA Drug Enforcement). Voluntary and mandated recalls affecting this drug.

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SafeCheck provides drug interaction information from FDA-approved product labeling (openFDA). This is for informational purposes only and is not medical advice. Always consult your healthcare provider before making medication decisions.