Used primarily in veterinary medicine and human healthcare as a broad-spectrum antibacterial agent effective against various Gram-positive and Gram-negative bacteria. It treats infections including urinary tract infections, respiratory tract infections, bloodstream infections, and meningococcal meningitis. Often combined with trimethoprim for synergistic action in bacterial infections or with pyrimethamine for toxoplasmosis, particularly in immunocompromised patients such as those with HIV. In burn care, sulfadiazine is applied topically as silver sulfadiazine to prevent bacterial and fungal infections in second- and third-degree burns. Due to rising antibiotic resistance, its systemic use has declined, but it remains valuable in specific clinical, veterinary, and topical applications.