Lamisil Once gives you a one-time topical ointment for treating the symptoms of Athlete's Foot. It contains the active ingredient Terbinafine Hydrochloride. How it works After the first application, the active ingredients contained in the cream stay on the skin for up to 13 days. This gives it time to completely fight off the fungi that cause infection and treat symptoms. Lamisil can be used as a preventative treatment against re-infection even months after use.