Terbinafine — NZ Medication Guide

What is Terbinafine?

Terbinafine (generic name: terbinafine hydrochloride) is a medication used primarily for fungal nail infections (onychomycosis) and skin fungal infections (tinea). Terbinafine oral tablets (250mg) are funded by Pharmac with Special Authority for dermatologist-confirmed onychomycosis. Cream and spray are available over-the-counter (OTC).

What is Terbinafine Used For?

Terbinafine is prescribed by healthcare professionals in New Zealand for the following indications:

• Onychomycosis (fungal nail infections) — toenail and fingernail
• Tinea pedis (athlete’s foot)
• Tinea corporis (ringworm of the body)
• Tinea cruris (jock itch)
• Tinea capitis (scalp ringworm) — primarily in children
• Tinea versicolor (pityriasis versicolor)

How Does Terbinafine Work?

Terbinafine is an allylamine antifungal that inhibits squalene epoxidase, an enzyme essential for fungal sterol biosynthesis. This leads to accumulation of toxic squalene and depletion of ergosterol (a key component of fungal cell membranes), causing fungal cell death. Terbinafine is fungicidal rather than fungistatic, contributing to high cure rates in nail infections.

How to Take Terbinafine

For nail infections: take 250mg once daily for 6 weeks (fingernails) or 12 weeks (toenails). Complete the full course — the nail takes months to grow out clear. Take with or without food. For skin infections: apply cream to the affected area twice daily for 1–4 weeks. Cream is available over-the-counter in NZ pharmacies.

Common Side Effects

• Nausea, diarrhoea, or abdominal discomfort
• Headache
• Skin rash or urticaria
• Taste disturbances — reduced or lost taste (dysgeusia)
• Musculoskeletal pain
• Mildly elevated liver enzymes

Serious Side Effects — Seek Medical Attention

• Hepatotoxicity — jaundice, dark urine, right-sided abdominal pain
• Severe skin reactions — Stevens-Johnson syndrome (rare)
• Blood disorders — neutropenia, thrombocytopenia (rare)
• Persistent taste loss (ageusia) that may last months
• Lupus-like syndrome (rare)

Drug Interactions

• CYP2D6 substrates (antidepressants, beta-blockers, antiarrhythmics) — terbinafine inhibits CYP2D6, increasing their levels
• Rifampicin — significantly reduces terbinafine levels
• Cimetidine — increases terbinafine blood levels
• Warfarin — monitor INR carefully during treatment
• Ciclosporin — terbinafine reduces ciclosporin levels

New Zealand Prescribing Information

In New Zealand, oral terbinafine requires Special Authority approval — it must be prescribed by or on the recommendation of a dermatologist for confirmed fungal nail infections. BPAC NZ recommends confirming the diagnosis with nail clippings or microscopy before oral treatment due to the prolonged course and liver side effect risk. Liver function tests should be performed at baseline for patients with pre-existing liver conditions.

Frequently Asked Questions

How long does terbinafine take to work for nail infections?

Oral terbinafine works by entering the nail bed and killing the fungus — but the nail takes 6–12 months to grow out clear after completing the 12-week course. Improvement is not visible during treatment. Completing the full course is essential for the best cure rates.

Can I buy terbinafine cream without a prescription?

Yes — terbinafine cream (Lamisil AT) is available over-the-counter at NZ pharmacies for skin fungal infections. Oral terbinafine tablets require a prescription and Special Authority approval for nail infections. Speak to your pharmacist if unsure which formulation suits your condition.

References & Further Information

The following New Zealand and international resources were used to inform this page:

• New Zealand Formulary — Terbinafine
• Pharmac — Special Authority for Terbinafine
• BPAC NZ — Fungal Nail Infections
• Medsafe — Terbinafine Data Sheet

Reviewed by a Registered Pharmacist — KiwiMeds New Zealand