Sulfamethoxazole tablet is an oral sulfonamide antibiotic, in combination with trimethoprim. It is used to treat a wide range of bacterial infections, including middle ear infections, urinary tract infections, lung infections, and intestinal infections. It is also used to treat and prevent a specific kind of pneumonia. Sulfamethoxazole and trimethoprim tablets are antibiotics that operate synergistically to prevent two successive processes in the manufacture of nucleic acids and proteins that are required for bacterial growth and division and using them together helps to limit the development of bacterial resistance. Common side effects of Trimethoprim and Sulfamethoxazole include nausea, vomiting, loss of appetite, and skin rash.d.