Colistin sulfate salt is primarily used as an antibiotic in both human and veterinary medicine. It is effective against Gram-negative bacterial infections, particularly those caused by multidrug-resistant strains such as Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae. In clinical settings, it is often reserved as a last-resort treatment for severe infections when other antibiotics have failed.

In veterinary medicine, it is commonly added to animal feed to prevent and treat bacterial infections in livestock, especially in poultry and swine. Additionally, it is used in aquaculture to control bacterial diseases in fish and shellfish.

Due to its potential nephrotoxicity and neurotoxicity, its use is carefully monitored, and it is typically administered via inhalation, intravenous, or topical routes under strict medical supervision. Its role in combating antibiotic-resistant infections underscores its importance in modern medicine.