Allylamine antifungal Pregnancy: No clinical experience in pregnant women; should not be used during pregnancy unless clearly necessary. Terbinafine is excreted into breast milk — should not be used during breast-feeding, and infants must not contact treated skin (including the breast).

Terbinafine

Brand names: Lamisil

Terbinafine is an allylamine antifungal used orally for dermatophyte infections of the skin and nails and topically for superficial fungal skin infections.

Auto-extracted from the source labelling — not yet independently clinician-verified. These values were distilled from the UK SPC (or the US label where noted) but have not had a clinician sign-off. Confirm against the current SmPC before prescribing.

Adult dose

Dose: Apply a thin layer once or twice daily (1% cream)

Route: Topical (cutaneous)

Frequency: Once or twice daily

Terbinafine 1% cream (external use only) — for adults and adolescents 12 years of age and older. Apply thinly on and around the affected skin and rub in gently. Typical duration: tinea pedis 1 week; tinea cruris and tinea corporis 1–2 weeks; cutaneous candidiasis 2 weeks; pityriasis versicolor 2 weeks. Relief of symptoms usually within a few days; re-evaluate the diagnosis if no improvement after 2 weeks. Not recommended for children below 12 years due to insufficient safety data. (This bundle is the topical cream formulation.)

Dose auto-extracted from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — not yet clinician-verified. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Hypersensitivity to terbinafine or to any of the excipients

Side effects

Skin exfoliation, pruritus (common)
Application-site pain and irritation (uncommon)
Skin lesion, scab, pigmentation disorder, erythema, skin burning sensation (uncommon)
Dry skin, contact dermatitis, eczema (rare)
Hypersensitivity and rash (frequency not known)

Interactions

No drug interactions are known with the topical forms of terbinafine

Clinical monograph

How it works

It inhibits the fungal enzyme squalene epoxidase, blocking ergosterol synthesis and leading to accumulation of squalene that is toxic to the fungal cell.

Prescribing in practice

Stop treatment and seek advice if symptoms of liver injury occur, as rare but serious hepatotoxicity has been reported with oral therapy.
Be alert for taste disturbance and rare severe cutaneous reactions, and counsel patients to report progressive rash.
It is a CYP2D6 inhibitor, so review co-prescribed drugs such as certain antidepressants and beta-blockers that are CYP2D6 substrates.

Monitoring

Check baseline liver function before oral treatment and review it periodically during prolonged courses.

Counselling the patient

Report nausea, abdominal pain, dark urine or yellowing of the skin or eyes.
Tell your team if you notice a change or loss of taste.
Nail infections may take several months to resolve after the course ends.

Evidence & guidelines

Oral terbinafine is established as a first-line treatment for dermatophyte onychomycosis, and the MHRA has highlighted the risks of hepatotoxicity and taste disturbance.

Reference: NICE CKS; MHRA; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Pathways