Sulfamethoxazole Trimethoprim Tablets 400 mg/80 mg, 500 Count (RX)Sulfamethoxazole Trimethoprim (often abbreviated as SMX TMP) is an antibiotic combination used to treat a variety of bacterial infections. The tablets containing 400 mg of sulfamethoxazole and 80 mg of trimethoprim are commonly used for: Urinary Tract Infections (UTIs): Effective in treating infections in the urinary system. Respiratory Infections: Such as bronchitis and certain types of pneumonia. Traveler's Diarrhea: Caused by specific bacteria.