Sulfanilamide is primarily used as an antibacterial agent, especially in topical treatments for skin infections, burns, and wound care. It works by inhibiting bacterial growth through interference with folic acid synthesis, which bacteria require for reproduction. It has been historically used in creams and ointments to prevent infection in second- and third-degree burns. In some cases, it is used to treat urinary tract infections and other localized infections when applied directly to affected areas. Though largely replaced by newer antibiotics for systemic use, it remains relevant in certain dermatological and veterinary applications due to its effectiveness against susceptible strains of bacteria.