• Bacterial infections

Bactrim Generic Name & Formulations

General Description

Sulfamethoxazole 400mg, trimethoprim 80mg; scored tabs.

Pharmacological Class

Sulfonamide + folic acid inhibitor.

See Also

How Supplied


Generic Availability


Bactrim Indications


Susceptible infections including UTIs (not for initial uncomplicated episodes), shigellosis, prophylaxis and treatment of Pneumocystis jiroveci pneumonia (PJP), travelers' diarrhea or acute exacerbations of chronic bronchitis in adults, acute otitis media in children.

Bactrim Dosage and Administration


1 DS tab or 2 regular tabs every 12 hours for 5 days (shigellosis, travelers' diarrhea), or 10–14 days (UTIs), or 14 days (bronchitis). PJP treatment: 15–20mg/kg per day trimethoprim (75–100mg/kg per day sulfamethoxazole) in equally divided doses every 6 hours for 14–21 days; PJP prophylaxis: one DS tab daily. Renal impairment (CrCl 15–30mL/min): reduce dose by ½; CrCl <15mL/min: not recommended.


<2months: see Contraindications. ≥2months: 8mg/kg per day trimethoprim (40mg/kg per day of sulfamethoxazole) in 2 divided doses at 12 hour intervals for 5 days (shigellosis) or 10 days (otitis media, UTIs). PJP treatment: as adult; PJP prophylaxis or renal impairment: see full labeling.

Bactrim Contraindications


History of drug-induced immune thrombocytopenia with use of trimethoprim and/or sulfonamides. Megaloblastic anemia due to folate deficiency. Pediatrics <2 months. Marked hepatic damage. Severe renal insufficiency when renal status cannot be monitored. Concomitant dofetilide.

Bactrim Boxed Warnings

Not Applicable

Bactrim Warnings/Precautions


Not for group A β-hemolytic strep. Avoid prolonged administration. Monitor CBCs, urine, and renal function. Hepatic or renal impairment. AIDS (increased risk of toxicities). Folate or G6PD deficiency. Severe allergy or bronchial asthma. Circulatory shock. Malnutrition. Porphyria or thyroid dysfunction. Disorders of potassium metabolism. Monitor for electrolyte abnormalities, hematologic toxicity. Maintain adequate hydration. Discontinue at 1st sign of skin rash or any other serious reaction. Elderly. Embryo-fetal toxicity. Pregnancy. Nursing mothers.

Bactrim Pharmacokinetics

See Literature

Bactrim Interactions


See Contraindications. Caution with concomitant CYP2C8, 2C9, or OCT2 substrates. May potentiate oral anticoagulants (eg, warfarin), hypoglycemics, phenytoin, methotrexate, digoxin; monitor. May be potentiated by indomethacin. May increase risk of thrombocytopenia with diuretics (esp. thiazides). Nephrotoxicity with cyclosporine in renal transplant. Megaloblastic anemia with >25mg/week doses of pyrimethamine. May antagonize tricyclic antidepressants. May interfere with assays for serum methotrexate, creatinine. PJP treatment: avoid leucovorin.

Bactrim Adverse Reactions

Adverse Reactions

Nausea, vomiting, anorexia, allergic skin reactions, blood dyscrasias (eg, megaloblastic anemia), hemolysis, hepatic or renal toxicity, crystalluria, pancreatitis, photosensitivity, drug fever, rash (may be serious, eg, Stevens-Johnson syndrome, toxic epidermal necrolysis, drug reaction with eosinophilia and systemic symptoms, others), hypoglycemia, hyperkalemia, hyponatremia; C. difficile associated diarrhea, thrombocytopenia.

Bactrim Clinical Trials

See Literature

Bactrim Note

Not Applicable

Bactrim Patient Counseling

See Literature