Bactrim DS is a combination antibiotic medication containing sulfamethoxazole and trimethoprim. It is primarily used to treat bacterial infections such as urinary tract infections, respiratory tract infections, ear infections, traveler’s diarrhea, and certain types of pneumonia. Bactrim DS works by inhibiting the growth of bacteria, and the combination of sulfamethoxazole and trimethoprim provides broader coverage against a variety of bacteria. It is available in tablet form and is typically taken orally.