Terbinafine is used to treat certain types of fungal infections (e.g., fingernail or toenail). It works by stopping the growth of fungus. This medication belongs to a class of drugs known as antifungals. Terbinafine is an antifungal medication that fights infections caused by fungus. Terbinafine topical (for the skin) is used to treat skin infections such as athlete's foot, jock itch, and ringworm infections. Terbinafine topical may also be used for purposes not listed in this medication guide.Terbinafine is an antifungal medication that fights infections caused by fungus. Terbinafine tablets are used to treat infections caused by fungus that affect the fingernails or toenails. Terbinafine oral granules are used to treat a fungal infection of scalp hair follicles in children who are at least above 12 year.