If you're using the cream, gel or spray, you'll usually need to use it for 1 to 2 weeks. Talk to your doctor if your symptoms do not get better within 2 weeks.

Terbinafine first became available in Europe in 1991 and in the United States in 1996. The U.S. Food and Drug Administration has approved the first generic versions of prescription Lamisil (terbinafine hydrochloride) tablets. The remaining patent or exclusivity for Lamisil expired on June 30, 2007.In a two-year oral carcinogenicity study in mice, no neoplastic or other abnormal findings attributable to treatment were made up to doses of 130 (males) and 156 (females) mg/kg a day. In a two-year oral carcinogenicity study in rats, an increased incidence of liver tumours was observed in males at the highest dosage level of 69mg/kg a day. The changes which may be associated with peroxisome proliferation have been shown to be species-specific since they were not seen in the carcinogenicity study in mice, dogs or monkeys. Like other allylamines, terbinafine inhibits ergosterol synthesis by inhibiting squalene epoxidase, an enzyme that catalyzes the conversion of squalene to lanosterol. In fungi, lanosterol is then converted to ergosterol; in humans, lanosterol becomes cholesterol. However, as fungi and animals diverged around 1.1 billion years ago - there is enough difference in this enzyme that terbinafine preferentially binds fungal squalene epoxidase, making it selective for inhibiting ergosterol production in fungi without significantly affecting cholesterol production in mammals. This is thought to fatally disrupt the fungal cell membrane. [ citation needed] Mikailov A, Cohen J, Joyce C, Mostaghimi A (March 2016). "Cost-effectiveness of Confirmatory Testing Before Treatment of Onychomycosis". JAMA Dermatology. 152 (3): 276–281. doi: 10.1001/jamadermatol.2015.4190. PMID 26716567. Central nervous system or neurological problems: Headaches, dizziness, vertigo, light-headedness, decreased concentration levels, paraesthesia (pins and needles)

Lamisil tablets are contraindicated for patients with chronic or active hepatic disease (see sections 4.3 Contraindications and 4.4 Special warnings and precautions for use). Gastrointestinal problems: Diarrhea, constipation, nausea, fullness, abdominal pain, indigestion, dyspepsia, gastritis, cholestasis, flatulence, altered stool colour, abdominal muscular pain The cream, gel and spray usually start to work within a week, and the tablets can take between 2 weeks and a few months to work.The duration of treatment for most patients is between 6 weeks and 3 months. Treatment periods of less than 3 months can be anticipated in patients with fingernail infection, toenail infection other than of the big toe, or patients of younger age. In the treatment of toenail infections, 3 months is usually sufficient although a few patients may require treatment of 6 months or longer. Poor nail outgrowth during the first weeks of treatment may enable identification of those patients in whom longer therapy is required. In India, terbinafine hydrochloride is available in topical form under the brand names Triabin by Medley Pharmaceuticals, Sebifin (Sun Pharma), Zimig (GSK Pharma) and mycoCeaze (Progreś Laboratories). MycoVa, developed by Apricus Biosciences, is a topical nail solution of terbinafine and DDAIP, which has completed three phase-III studies for the treatment of onychomycosis.