Lamisil (Terbinafine) 250 mg Tablets: Prescription Oral Antifungal for Nail Fungus (Onychomycosis), Ringworm & Athlete’s Foot

Information last reviewed: May 2026 — for educational purposes only.

Terbinafine, marketed as Lamisil, is an allylamine antifungal available in two very different forms. Oral terbinafine 250 mg tablets require a prescription and are used primarily to treat fungal nail infections (onychomycosis) caused by dermatophytes. Topical terbinafine (cream, gel, or spray) at 1% concentration is available over the counter under the Lamisil brand and generics for skin fungal infections such as ringworm (tinea corporis), athlete’s foot (tinea pedis), and jock itch (tinea cruris). These are two distinct products with different dosing, uses, and safety considerations.

What Does Oral Terbinafine Treat?

Oral terbinafine 250 mg tablets are FDA-approved for:

• Onychomycosis of the toenails — 250 mg once daily for 12 weeks
• Onychomycosis of the fingernails — 250 mg once daily for 6 weeks

These are the only FDA-approved oral indications. After completing treatment, the nail continues to grow out, and visible improvement takes several more months as healthy nail replaces the infected portion. Cure rates are generally 50–70% at 12 months for toenail onychomycosis.

Oral terbinafine is also used off-label by dermatologists for tinea capitis (scalp ringworm), particularly when topical treatment has failed. It is fungicidal — it kills the fungus rather than merely inhibiting its growth — and is the preferred oral option for dermatophyte infections due to this mechanism.

Liver Monitoring Requirement

Because oral terbinafine is hepatically metabolised and has caused rare but serious hepatic events (liver failure, including cases requiring transplant), the FDA recommends that baseline liver function tests (LFTs) be obtained before starting treatment in patients with hepatic disease. Patients should be warned to report symptoms of liver toxicity: persistent nausea, loss of appetite, unusual fatigue, right upper-quadrant pain, jaundice, or dark urine. Oral terbinafine is contraindicated in patients with chronic or active liver disease.

Strengths and Formulations

• Oral tablets 250 mg (Rx) — Lamisil or generic terbinafine; once daily for 6 or 12 weeks depending on indication; can be taken with or without food
• Topical cream 1% (OTC) — Lamisil AT; applied once or twice daily for 1–2 weeks for skin fungal infections
• Topical gel 1% (OTC) — Lamisil AT Gel; similar indications and duration
• Topical spray 1% (OTC) — Lamisil AT Spray; convenient for large areas such as athlete’s foot
• Oral granules 125 mg / 187.5 mg (Rx) — Granules sprinkled on food; approved for tinea capitis (scalp ringworm) in children 4 years and older

CYP2D6 Drug Interaction

Terbinafine is a potent inhibitor of the CYP2D6 enzyme. This is clinically significant for patients on medications metabolised by CYP2D6, including certain antidepressants (TCAs, some SSRIs), antipsychotics, beta-blockers (metoprolol, propranolol), and codeine. Concurrent use may increase plasma levels of these drugs. Prescribers should review the patient’s medication list carefully before initiating oral terbinafine.

Price of Generic Terbinafine

Generic terbinafine 250 mg tablets are widely available and affordable. A 12-week course (84 tablets) typically costs $30–$60 with a pharmacy discount card in the US. OTC Lamisil AT topical products are available without a prescription at most pharmacies and retail stores.

Frequently Asked Questions

How long before I see results from oral terbinafine for nail fungus?

The drug course is 6 weeks (fingernails) or 12 weeks (toenails), but visible nail improvement lags behind treatment completion because infected nail must grow out and be replaced by healthy nail. Most patients see significant improvement at 6 months and assess final outcomes at 12 months. Toenails grow slowly (about 1mm per month), so patience is required.

Can oral terbinafine cause taste changes?

Yes. Taste disturbance — including partial or complete loss of taste (ageusia or dysgeusia) — is a recognised side effect of oral terbinafine, affecting roughly 1% of patients. In rare cases, taste loss may be prolonged. Patients should be made aware of this possibility before starting treatment and should report it to their prescriber if it occurs.

Is OTC terbinafine cream enough to treat nail fungus?

No. Topical antifungals, including terbinafine cream, do not penetrate the nail plate adequately to treat onychomycosis. OTC topicals are effective only for skin fungal infections. Nail fungus requires oral treatment (terbinafine tablets or itraconazole) or prescription-strength nail lacquer (ciclopirox or amorolfine), both of which need a prescriber’s authorisation.

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