Medical Editor: John P. Cunha, DO, FACOEP
Trimethoprim [Brand names: Trimpex (Discontinued Brand), Proloprim (Discontinued Brand), Primsol] is an antibiotic used to treat bacterial infections. Trimethoprim is often combined in a single pill with sulfamethoxazole. Trimethoprim is available in generic form. Common side effects of trimethoprim include:
- itching and rash,
- stomach upset,
- loss of appetite,
- changes in taste,
- skin sensitivity to sunlight,
- swollen tongue, and
The usual oral adult dosage of Trimethoprim is 100 mg every 12 hours or 200 mg trimethoprim every 24 hours, each for 10 days. Trimethoprim may interact with dofetilide, digoxin, methotrexate, phenytoin, procainamide, and it may decrease the effectiveness of hormonal birth control. Tell your doctor all medications you are taking. Trimethoprim should be used only when prescribed during pregnancy. Trimethoprim passes into breast milk. While there have been no reports of harm to nursing infants, consult your doctor before breastfeeding.
Our Trimethoprim Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Rash, pruritus, and phototoxic skin eruptions. At the recommended dosage regimens of 100 mg b.i.d. or 200 mg q.d. each for 10 days, the incidence of rash is 2.9% to 6.7%. In clinical studies which employed high doses of trimethoprim (trimethoprim (trimethoprim tablet) tablet) , an elevated incidence of rash was noted. These rashes were maculopapular, morbilliform, pruritic, and generally mild to moderate, appearing 7 to 14 days after the initiation of therapy.
Epigastric distress, nausea, vomiting, and glossitis. Elevation of serum transaminase and bilirubin has been noted, but the significance of this finding is unknown. Cholestatic jaundice has been rarely reported.
Aseptic meningitis has been rarely reported.
Fever, and increases in BUN and serum creatinine levels.
Read the entire FDA prescribing information for Trimethoprim (Trimethoprim Tablet)