Bactrim Uses

Bactrim is used to treat infections caused by bacteria, including urinary tract infections, middle ear infections in children, shigellosis, traveler’s diarrhea, acute exacerbation of chronic bronchitis in adults, and to prevent pneumonia in adults with compromised immune systems. 

Antibiotics like Bactrim can only treat bacterial infections. They do not treat viral infections like the common cold or flu. To reduce the incidence of drug-resistant bacteria and maintain effectiveness, doctors prescribe antibiotics only when you have a proven or strongly suspected bacterial infection.

There may be other uses of Bactrim — your pharmacist or healthcare professional can give you further drug information.

Bactrim Mechanism of Action

Bactrim works by blocking the synthesis of proteins and nucleic acids essential to many bacteria.  

Bactrim Doses

Bactrim contains sulfamethoxazole and trimethoprim 400/80 mg, and Bactrim DS (double strength) contains sulfamethoxazole and trimethoprim 800/160 mg.

• For UTIs in adults: The usual dose is 2 Bactrim tablets or 1 Bactrim DS tablet every 12 hours (twice a day) for 10-14 days.
• For acute exacerbation of chronic bronchitis in adults: The usual dose is 2 Bactrim tablets or 1 Bactrim DS tablet every 12 hours (twice a day) for 14 days.
• For traveler’s diarrhea in adults: The recommended dose is 2 Bactrim or 1 Bactrim DS every 12 hours for 5 days.
• For shigellosis in adults: The usual dose is 2 Bactrim tablets or 1 Bactrim DS tablet twice a day for 5 days.
• For UTIs, middle ear infections, and shigellosis in children: Bactrim dose is based on the child’s body weight and is usually 40 mg/kg sulfamethoxazole and 8 mg/kg trimethoprim daily, given in two divided doses (every 12 hours). Treatment lasts 10 days for UTIs and middle ear infections and 5 days for shigellosis.
• For Pneumocystis carinii pneumonia in adults and children: The recommended dosage is 75 to 100 mg/kg sulfamethoxazole and 15 to 20 mg/kg trimethoprim every 24 hours given in equally divided doses every 6 hours for 14-21 days.
• To prevent pneumonia in immunocompromised patients: The recommended dosage is 1 Bactrim DS tablet daily in adults. In children, the recommended dose is 750 mg/m2/day of sulfamethoxazole and 150 mg/m2/day of trimethoprim given in two divided doses on three consecutive days per week. Children's maximum daily dose should not exceed 1600 mg/320 mg of sulfamethoxazole and trimethoprim.