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Treatments for toenail fungus:
Terbinafine (Lamisil)

Generic Name: Terbinafine hydrochloride
Brand Name(s): Lamisil
Dosage Form: tablet

What is Terbinafine?

Terbinafine, marketed under the brand name Lamisil® and available in generic form, is an antifungal drug used to treat onychomycosis due to dermatophytes. In the U.S., terbinafine tablets are available only by prescription. The active ingredient in terbinafine tablets is the antifungal compound terbinafine hydrochloride, a synthetic allylamine derivative. Terbinafine tablets also contain inactive ingredients: colloidal silicon dioxide, NF; hypromellose, USP; magnesium stearate, NF; microcrystalline cellulose, NF; sodium starch glycolate, NF.

Terbinafine (Lamisil)

Prior to beginning treatment with terbinafine, the diagnosis of onychomycosis should be confirmed by submitting nail specimens for laboratory testing (KOH preparation, fungal culture, or nail biopsy).

Some individuals should not take terbinafine tablets. These include people with hypersensitivity to terbinafine hydrochloride or to any other ingredients in the tablets, patients with chronic or active liver disease, patients with kidney problems, pregnant women, nursing mothers and children. See Warnings and Precautions below.

Dosage and Administration of Terbinafine

The recommended course of treatment for patients with toenail onychomycosis is one 250 mg terbinafine hydrochloride tablet taken once daily for 12 weeks. The effect of the medication normally will not be fully seen until several months after completion of treatment due to the slow growth pattern of toenails. Since toenails grow more slowly as a person ages, older individuals may not have fully clear nails for as long as a year after beginning treatment.

How Does Terbinafine Work on Toenail Fungus?

Terbinafine is thought to work by inhibiting an enzyme (squalene epoxidase) that is needed to enable the formation of ergosterol. Ergosterol is an essential component of fungal cell membranes.

Is Terbinafine Effective Against Toenail Fungus?

Terbinafine has been shown to be active against most strains of the dermatophytes Trichophyton mentagrophytes and Trichophyton rubrum both in vitro and in clinical infections.

In laboratory tests, terbinafine satisfactorily inhibits most strains of Candida albicans, Epidermophyton floccosum, and Scopulariopsis brevicaulis. However, the lab results of terbinafine in treating toenail infections due to these microorganisms have not been established in well-controlled clinical trials. Clinical results do not always yield the same results achieved in a laboratory environment.

The results of one study of patients taking terbinafine for toenail fungus, as evaluated at week 48 (after 12 weeks of terbinafine treatment and 36 weeks of post-treatment nail growth), found that 70% of patients were cured (defined as having both a negative KOH smear plus a negative culture).

Warnings and Precautions When Taking Terbinafine

Clinical studies, combined with data from actual usuage over many years, have confirmed that terbinafine is a relatively safe treatment for toenail fungus. Like any medication, however, there are known side effects in some patients. In addition, certain patients in particular circumstance should not be given terbinafine.

Side Effects of Terbinafine

All medicines may cause side effects, but most people have no, or mild, short-term, side effects from terbinafine. The most common side effects when using terbinafine are headache, diarrhea, indigestion and taste disturbance (including taste loss).

In rare cases, side effects of terbinafine have included allergic reactions (rash, hives, itching, etc...), liver problems and vision changes. If there are any signs of these more severe side effects, you should seek medical attention immediately.

Impaired Liver or Kidneys

Terbinafine tablets are not recommended for patients who have chronic or active liver disease. Before your doctor prescribes terbinafine tablets, he or she should evaluate your liver function. After the terbinafine treatment begins, if you experience persistent nausea, fatigue, vomiting, anorexia, right upper abdominal pain or jaundice, pale stools or dark urine you should let your doctor know immediately. If these symptoms appear, you should discontinue taking oral terbinafine, and your liver function should be immediately assessed.

In patients with impaired kidney functions, the use of terbinafine has not been adequately studied, and therefore, is not recommended.


Studies of the effects of terbinafine on reproduction in rabbits and rats have revealed no evidence of impaired fertility or harm to the fetus. There are no well-controlled clinical studies in pregnant women, however. Because animal reproduction studies do not always accurately predict human response, and because it is a simple matter to delay treatment of toenail fungus until after the pregnancy, it is recommended that terbinafine treatment not be begun during pregnancy.

Nursing Mothers

After oral administration, terbinafine is present in breast milk of nursing mothers. Terbinafine treatment is not recommended in nursing mothers.

Pediatric Use

The safety and efficacy of terbinafine tablets have not been established in pediatric patients.

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