Terbinafine hydrochloride is a broad-spectrum antifungal drug used in dermatology. It can specifically disturb the late biological decomposition of fungal sterols, selectively inhibit the activity of squalene cyclooxygenase, and block the reaction of squalene epoxidation in the process of fungal cell membrane formation, so as to kill or inhibit fungi. It is suitable for the treatment of skin candidiasis, such as tinea manus, tinea pedis, tinea cruris, tinea corporis and tinea versicolor. It is also the best drug for the treatment of onychomycosis.