Is Lamisil (terbinafine) used to treat toenail fungus (onychomycosis)?

Lamisil (Terbinafine) for Toenail Fungus

Yes, Lamisil is the brand name for terbinafine, which is the first-line treatment for toenail fungus (onychomycosis) caused by dermatophytes. 1, 2

What is Lamisil/Terbinafine?

• Terbinafine (brand name Lamisil) is a prescription oral antifungal medication specifically FDA-approved for treating fungal infections of toenails and fingernails caused by dermatophytes. 2

• Terbinafine works by inhibiting squalene epoxidase, an enzyme critical for fungal cell wall formation, resulting in both fungal cell death (fungicidal effect) and prevention of fungal growth (fungistatic effect). 1

• It has the lowest minimum inhibitory concentration (MIC) of all available systemic antifungals against dermatophytes, with an MIC equal to its minimal fungicidal concentration (MFC), making it truly fungicidal. 1

Standard Dosing Regimen

For toenail onychomycosis, take terbinafine 250 mg once daily for 12 weeks. 3, 2

• For fingernail infections, the treatment duration is shorter at 6 weeks. 3, 2

• The medication can be taken with or without food. 3, 2

• The optimal clinical effect appears months after completing treatment because healthy nail must grow out to replace the infected nail. 2

Why Terbinafine is First-Line Treatment

Terbinafine demonstrates superior efficacy compared to all other oral antifungals for dermatophyte toenail infections, with approximately twice the cure rate of itraconazole. 1, 4

• In the landmark L.I.ON. study, mycologic cure rates were 76% with terbinafine versus 38% with itraconazole after 12 weeks of treatment. 4

• Complete cure rates (both mycologic and clinical cure) were also approximately double with terbinafine compared to itraconazole. 4

• At 5-year follow-up, terbinafine maintained superior efficacy with lower relapse rates (23% mycologic relapse) compared to itraconazole (53% mycologic relapse). 4

• Terbinafine has the highest quality of evidence rating (A-I) from the British Association of Dermatologists. 1

Pre-Treatment Requirements

Your doctor must obtain nail specimens for laboratory confirmation (KOH preparation, fungal culture, or nail biopsy) before starting treatment. 2

• Baseline liver function tests (ALT and AST) are required before initiating terbinafine. 3, 5, 2

• Complete blood count is recommended, particularly if you have a history of hepatitis, heavy alcohol use, or blood disorders. 3

Absolute Contraindications

Do not take terbinafine if you have:

• Active or chronic liver disease 1, 3, 5, 2
• History of allergic reaction to oral terbinafine 5, 2
• Lupus erythematosus 1, 3, 5

Important Safety Warnings

Stop terbinafine immediately and contact your doctor if you develop any of these symptoms:

• Liver problems: persistent nausea, loss of appetite, fatigue, vomiting, right upper abdominal pain, jaundice (yellowing of skin/eyes), dark urine, or pale stools 2

• Serious skin reactions: hives, mouth sores, blistering and peeling of skin, swelling of face/lips/tongue/throat, difficulty swallowing or breathing (Stevens-Johnson syndrome or toxic epidermal necrolysis have been reported) 3, 2

• Taste or smell disturbances: change in taste or loss of taste occurs in approximately 1 in 400 patients and may become permanent 1, 2

• Depressive symptoms: feeling sad or worthless, changes in sleep pattern, loss of energy or interest in daily activities, restlessness, or mood changes 2

Drug Interactions

Terbinafine has minimal drug interactions compared to azole antifungals (like itraconazole), making it safer for patients on multiple medications. 1, 3

• The main interaction concern is with drugs metabolized by cytochrome P450 2D6, including certain antidepressants, beta-blockers, and antiarrhythmics. 3

• Plasma concentrations are reduced by rifampin and increased by cimetidine. 1

Common Side Effects

• Gastrointestinal complaints (most common), dermatological events, and headache occur in approximately 10.5% of patients. 4

• Nausea and rashes occur in 8-15% of patients. 1

• Serious adverse events occur in only 0.04% of patients. 3

Follow-Up and Expected Timeline

You should be re-evaluated 3-6 months after starting treatment, and additional treatment may be needed if the infection persists. 3, 5

• Terbinafine persists in the nail for up to 6 months after treatment completion due to its long half-life and lipophilic properties, allowing continued antifungal activity. 3

• Mean time to overall success is approximately 10 months for toenail infections. 2

• For patients achieving clinical cure, the relapse rate at one year after completing therapy is approximately 15%. 2

Common Pitfall to Avoid

Do not confuse treatment duration with cure timeline. While you only take the medication for 12 weeks, you won't see the full clinical effect until months later when the healthy nail has completely grown out. 2 This is normal and does not indicate treatment failure.