Objective: Terbinafine hydrochloride (TFH) is an allyl amine derivative used to treat fungal infections like pityriasis versicolor, dermatophytosis, and tineacapitis. It inhibits squalenceepoxidase, an enzyme involved in fungal cell wall formation, leading to cell death. Terbinafine, the industry leader in topical antifungals, has captured 80% of the projected US$1.5 billion worldwide market for onychomycosis. Terbinafine is the only oral allylamine sold commercially, and other formulations have been added. This study evaluates the mycology and pharmacology of terbinafine, focusing on dermatophytosis and its role in non-dermatophyte infections