What is Terbinafine?
Terbinafine is an allylamine antifungal medicine used primarily to treat dermatophyte fungal infections of the skin and nails. It is authorised under product- and country-specific conditions and is considered a first-line treatment for fungal nail infection (onychomycosis) and tinea infections.
Beyond fingernail and toenail onychomycosis, terbinafine is also prescribed for tinea cruris (jock itch / groin ringworm), tinea pedis (athlete’s foot), and tinea corporis (ringworm of the body). These are all dermatophyte fungal infections — distinct from candidal yeast infections, which are treated with azole antifungals such as clotrimazole or fluconazole.
Terbinafine is available as oral tablets (250 mg) for systemic treatment of nail and widespread skin infections, and as topical cream (1%) for localised skin fungal infections.
How does Terbinafine work?
Terbinafine is an allylamine antifungal that works by inhibiting squalene epoxidase, a fungal enzyme involved in the early stages of ergosterol biosynthesis. This mechanism differs from azole antifungals (fluconazole, clotrimazole), which act at a later stage in the same biosynthetic pathway.
The process:
- Squalene epoxidase inhibition: Terbinafine inhibits the enzyme that converts squalene to squalene epoxide, an early step in ergosterol synthesis.
- Squalene accumulation: The block causes squalene to accumulate within the fungal cell to toxic levels, as squalene epoxide cannot be formed.
- Ergosterol depletion: The fungal cell membrane becomes deficient in ergosterol, disrupting membrane integrity.
- Dual mechanism of toxicity: Both the depletion of ergosterol and the toxic accumulation of squalene contribute to fungal cell death.
- Fungicidal against dermatophytes: Terbinafine is fungicidal (kills fungi) against dermatophytes at clinically relevant concentrations, contributing to its high cure rates for nail infections.
Why terbinafine is selective for fungi: Squalene epoxidase is present in both humans and fungi, but terbinafine has approximately 10,000 times greater selectivity for the fungal enzyme than the human enzyme.
Limited Candida activity: Terbinafine is predominantly fungistatic (growth-inhibiting) rather than fungicidal against Candida species, which is why it is not the preferred choice for candidal infections.
Who is Terbinafine for?
Oral terbinafine is indicated for:
- Onychomycosis (fungal nail infection): Caused by dermatophytes (Trichophyton rubrum, T. mentagrophytes) — the most common indication
- Extensive tinea pedis (athlete’s foot): When topical treatment is insufficient
- Tinea corporis (ringworm) and tinea cruris (groin ringworm): For widespread or treatment-resistant cases
Topical terbinafine cream 1% is indicated for:
- Localised tinea pedis (athlete’s foot)
- Tinea corporis (ringworm)
- Tinea cruris (jock itch / groin ringworm)
- Pityriasis versicolor (caused by Malassezia species)
Not appropriate for:
- Vaginal candidiasis (use clotrimazole or fluconazole)
- Oral candidiasis (use nystatin or fluconazole)
- Patients with severe liver disease (oral terbinafine is contraindicated)
- Pregnancy (avoid systemic terbinafine unless clearly necessary; topical use may be acceptable in some cases — doctor assessment required)
Dosage
Oral Terbinafine (systemic treatment)
| Indication | Dose | Duration |
|---|---|---|
| Fingernail onychomycosis | 250 mg once daily | 6 weeks |
| Toenail onychomycosis | 250 mg once daily | 12 weeks |
| Tinea pedis (extensive) | 250 mg once daily | 2–6 weeks |
| Tinea corporis / tinea cruris (extensive) | 250 mg once daily | 2–4 weeks |
Oral terbinafine can be taken with or without food.
Topical Terbinafine Cream 1%
| Indication | Application | Duration |
|---|---|---|
| Tinea pedis (athlete’s foot) | Once or twice daily | 1–2 weeks |
| Tinea corporis / cruris | Once or twice daily | 1–2 weeks |
| Pityriasis versicolor | Once daily | 2 weeks |
Apply a thin layer to the affected area and 2–3 cm of surrounding skin. Allow to dry.
Side effects
Oral Terbinafine
Very common side effects (at least 1 in 10 people):
- Gastrointestinal symptoms: nausea, diarrhoea, abdominal discomfort, loss of appetite
- Headache
- Skin rash and urticaria
- Joint and muscle pain (arthralgia, myalgia)
Common side effects (at least 1 in 100 but fewer than 1 in 10 people):
- Taste disturbances (dysgeusia) — including loss of taste; usually reversible after stopping but can persist
- Dizziness
Rare side effects (at least 1 in 10,000 but fewer than 1 in 1,000 people):
- Elevated liver enzymes (liver function monitoring is recommended)
Serious effects and warning signs:
- Hepatotoxicity: Serious liver reactions including cholestasis, hepatitis, and very rarely liver failure — monitor for jaundice, dark urine, pale stools, persistent nausea
- Severe skin reactions: Stevens-Johnson syndrome, toxic epidermal necrolysis (very rare)
- Haematological effects: Agranulocytosis, pancytopenia (very rare)
- Taste loss: Severe, prolonged taste disturbance or complete taste loss has been reported; may last months after stopping treatment
Topical Terbinafine
Generally well tolerated. Local skin reactions (burning, itching, redness) at the application site are uncommon.
Terbinafine vs alternative antifungal treatments for nail infection
| Treatment | Route | Duration | Cure Rate (Toenail) | Notes |
|---|---|---|---|---|
| Terbinafine | Oral | 12 weeks | ~60–80% | First-line; fungicidal |
| Itraconazole | Oral (pulse) | 3 months | ~50–70% | Alternative; drug interactions |
| Fluconazole | Oral | 6–12 months | ~40–60% | Longer course; weekly dosing |
| Amorolfine | Topical nail lacquer | 6–12 months | ~35–50% | For mild cases; no liver risk |
Oral terbinafine is generally considered the most effective oral treatment for toenail onychomycosis due to its fungicidal activity against dermatophytes.
Online assessment for Terbinafine
Oral Terbinafine is a prescription-only medicine (POM) in all EU member states. It cannot legally be dispensed without a valid prescription from a licensed medical professional.
Prescrivia operates as a technology intermediary: we do not prescribe medicines, employ doctors, or sell medicines. Our platform connects patients with independent doctors who can conduct confidential online health assessments.
Availability of an online assessment, prescribing, dispensing and delivery depends on the medicine, country and applicable law. Spain prohibits distance sale of prescription medicines; a catalogue entry or cross-border prescription does not establish a right to delivery. An in-person examination or testing may be required.
The process, where legally and clinically available:
- Complete a health assessment: Describe the affected nails or skin, duration of infection, and any relevant medical history including liver disease or other medications.
- Doctor review: An independent doctor reviews your assessment. If terbinafine is clinically appropriate, they may issue a prescription.
- Pharmacy fulfilment: The prescription is sent to a pharmacy partner to assess dispensing and any supply under the applicable country rules.
Important: Prescrivia does not guarantee that a prescription will be issued. All prescribing decisions are made independently by qualified medical professionals.
Important safety information
Do not take oral Terbinafine if you:
- Have active or chronic liver disease
- Have severe kidney disease
- Are pregnant (avoid unless clearly necessary — discuss with doctor)
- Are breastfeeding (terbinafine passes into breast milk — avoid)
- Are allergic to terbinafine
Tell your doctor before taking Terbinafine if you:
- Have any history of liver problems
- Have autoimmune conditions such as lupus (terbinafine has been associated with triggering or worsening cutaneous and systemic lupus erythematosus)
- Are taking other medicines metabolised by the CYP2D6 enzyme, including antidepressants (TCAs, SSRIs), antipsychotics, and beta-blockers (terbinafine inhibits CYP2D6)
- Are taking ciclosporin (terbinafine may reduce ciclosporin blood levels)
- Are taking caffeine-containing medicines (terbinafine reduces caffeine metabolism)
Sources
Medical information on this page is based on the following sources:
- World Health Organization (WHO). WHO Model List of Essential Medicines. 22nd edition, 2021. who.int
- Gupta AK, et al. Onychomycosis: a review of clinical features, epidemiology, and treatment. Journal of the European Academy of Dermatology and Venereology. 2020.
The content-edit date does not certify a clinical review. It is provided for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for advice relevant to your individual health circumstances.
Frequently asked questions
- What is Terbinafine used for?
- Terbinafine is an antifungal medicine primarily used to treat dermatophyte fungal infections of the nails (onychomycosis) and skin. Common conditions treated include fungal nail infection (tinea unguium), athlete's foot (tinea pedis), ringworm (tinea corporis), and fungal groin infection (tinea cruris). It is available as oral tablets and topical cream.
- How long does oral Terbinafine take to work for nail fungal infection?
- Oral terbinafine is taken for 6 weeks for fingernail infections and 12 weeks for toenail infections. However, because nails grow slowly, visible improvement may not be apparent for several months after completing treatment. Full nail clearance can take 6–12 months or more after the course ends, as the healthy nail gradually grows out replacing the infected nail.
- Is Terbinafine effective against vaginal thrush?
- No. Terbinafine is highly effective against dermatophyte fungi (Trichophyton, Microsporum, Epidermophyton species) but has limited activity against Candida species, which cause vaginal thrush. For vaginal candidiasis, antifungals such as clotrimazole (Canesten Gyno) or fluconazole (Diflucan) should be used instead.
- What are the liver-related risks with oral Terbinafine?
- Oral terbinafine can rarely cause liver enzyme elevations and, very rarely, serious hepatic events including liver failure. The EMA recommends that liver function should be assessed before starting oral terbinafine, and patients should be monitored for signs of liver problems during treatment. Terbinafine should be discontinued if liver problems develop.
- How does an online assessment for Terbinafine work?
- Oral terbinafine is a prescription-only medicine in all EU member states. Topical terbinafine cream may be available without prescription in some countries for certain skin conditions. You can access oral terbinafine through online intermediary platforms connecting you with independent doctors for a confidential assessment. Availability depends on country rules and clinical assessment; this is not a delivery guarantee.
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Intermediary notice: Prescrivia connects patients with independent doctors and licensed pharmacies. We do not provide medical advice, employ doctors, or sell medicines. All medical decisions are made by independent healthcare professionals, and prescription-only medicines require a valid prescription. Treatment is not guaranteed — whether a prescription is issued depends on an independent doctor's clinical assessment.
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