Trimethoprim is an antibiotic medication primarily used to treat bacterial infections, particularly those affecting the urinary tract. It works by inhibiting the growth of bacteria, making it effective against various strains that cause infections. This medication is often prescribed alone or in combination with sulfamethoxazole, another antibiotic, to enhance its effectiveness. Trimethoprim is usually taken orally in tablet form and is important to complete the full course of treatment to prevent the development of antibiotic resistance.