Fusimar H is a combination of two medicines: Hydrocortisone and Fusidic Acid which treat skin infections. Hydrocortisone is a steroid medicine. It blocks the production of certain chemical messengers (prostaglandins) that make the skin red, swollen and itchy. Fusidic Acid is an antibiotic. It stops bacterial growth by preventing synthesis of essential proteins required by bacteria to carry out vital functions.