Bactrim (sulfamethoxazole / trimethoprim) is a sulfa antibiotic that treats bacterial infections. The most common Bactrim side effects are nausea, diarrhea, and skin changes. Bactrim and Bactrim DS are antibiotics used to treat ear infections, urinary tract infections, bronchitis, traveler's diarrhea, shigellosis, and Pneumocystis jiroveci pneumonia. Bactrim (sulfamethoxazole-trimethoprim) is used for uncomplicated UTIs, community-acquired MRSA skin and soft tissue infections, PCP pneumonia prophylaxis in immunocompromised patients, traveler's diarrhea, and certain respiratory infections where local susceptibility supports its use. Learn about uses, side effects, dosage, and more for Bactrim. It's a prescription oral tablet used to treat certain types of infection in adults and some children. Medscape - Indication-specific dosing for Bactrim, Bactrim DS, Septra, Septra DS, Cotrim, cotrimoxazole, Sulfatrim (trimethoprim, sulfamethoxazole), frequency-based adverse effects. Bactrim, the fixed-dose combination of sulfamethoxazole (SMX) and trimethoprim (TMP) in a 5:1 weight ratio (typically 400 mg SMX / 80 mg TMP per standard tablet), represents a landmark example of rational combinatorial antibiotic design based on mechanistic pharmacology. Trimethoprim/sulfamethoxazole, sold under the trade names Bactrim, Cotrim (a short form of the British Approved Name, Co-trimoxazole) and Septra, among others, is a fixed-dose combination antibiotic medication used to treat a variety of bacterial infections. [2] Bactrim (Trimethoprim and Sulfamethoxazole) may treat UTI, side effects, dosage, drug interactions, warnings, patient labeling, and more Find patient medical information for Sulfamethoxazole/Trimethoprim (Bactrim, Septra, others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user. Sulfamethoxazole and trimethoprim combination is used to treat infections including urinary tract infections, middle ear infections (otitis media), bronchitis, traveler's diarrhea, and shigellosis (bacillary dysentery).