Terbinafine

Allylamine antifungal (systemic and topical)

ATC code: D01BA02

Brand names: Lamisil, Terbinex

Updated 24 Sep 2026 · Methodology

Indications

Onychomycosis

First line

Oral terbinafine 250 mg/day is first-line therapy for onychomycosis with matrix involvement or more than 50% nail plate disease. CKS Fungal nail infection 2023 and BAD 2018 recommend continuous courses: 6 weeks for fingernails and 12 weeks for toenails. Complete cure rates: toenails about 70%, fingernails about 80%. Pulse regimens (1 week on each month for 3–4 cycles) showed comparable efficacy in the Warshaw 2005 trial, but real-world adherence is lower and relapse rates higher; AEDV considers continuous therapy the standard. Topical forms (cream, spray, gel) do not penetrate the nail plate and are ineffective for onychomycosis. Monitor ALT and AST at 4–6 weeks because of drug-induced liver injury risk. If terbinafine was prescribed as a cream for nail fungus or as a short pulse course without discussion of continuous therapy, consider seeking a second opinion.

Sources

ICD-10: B35.1 · ICD-11: EE12.1

Superficial fungal infections

First line

Superficial dermatophyte infections (tinea pedis, corporis, cruris, capitis) are treated with terbinafine according to site. Tinea pedis and corporis: 1% cream once or twice daily for 1–2 weeks. Tinea capitis in children: oral tablets for 4–6 weeks, 2023 lists terbinafine as first line (replacing griseofulvin). Tinea unguium and persistent widespread forms: systemic tablets, as for onychomycosis. AEDV notes that tinea cruris and corporis usually respond to topical therapy; oral tablets are used when more than 5% of body surface is involved or topical therapy fails.

Sources

ICD-10: B35 · ICD-11: 1F28

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

Allylamine. Inhibits fungal squalene epoxidase, blocking ergosterol synthesis and accumulating toxic squalene in the cell wall. Fungicidal against dermatophytes (Trichophyton, Microsporum, Epidermophyton); fungistatic against yeasts (Candida). Systemic terbinafine concentrates in keratin of nails, hair and stratum corneum for weeks after the last dose. Metabolised via CYP1A2, 2C9 and 3A4; plasma half-life 17 hours, elimination from skin and nails extends to 200–400 hours.

Safety

Contraindications

Hypersensitivity to terbinafine
Active liver disease or ALT/AST more than 3× upper limit of normal
Severe renal impairment (CrCl below 50 mL/min) for systemic forms
Children under 2 years of age

Serious adverse effects

Drug-induced liver injury, in rare cases fulminant hepatic failure
Agranulocytosis and thrombocytopenia
Depression and suicidal ideation
Stevens-Johnson syndrome and toxic epidermal necrolysis
DRESS syndrome

Common adverse effects

Dyspepsia, nausea, diarrhoea
Headache
Skin rash and pruritus
Taste disturbance or loss (may persist for weeks after discontinuation)
Asymptomatic ALT and AST elevation

Pregnancy: can you take Terbinafine?

AEMPS summary of product characteristics (section 4.6): animal studies have not shown teratogenic or embryofetotoxic potential for terbinafine, and no malformations have been observed in humans to date. Because clinical experience in pregnant women is very limited, terbinafine tablets (Terbinafina Normon 250 mg) are used in pregnancy only if the woman's condition requires oral terbinafine and the expected benefit for the mother outweighs the possible risk to the fetus. For the cream (Lamisil 10 mg/g summary of product characteristics, section 4.6), there is no clinical experience in pregnant women, and animal fetal toxicity studies do not suggest adverse effects. The cream is used in pregnancy only if strictly necessary.

Breastfeeding: can you take Terbinafine?

Systemic terbinafine is Hale L3 (probably compatible); it transfers into milk with RID about 4%. Short courses are acceptable under paediatric monitoring. Topical forms are Hale L2; do not apply to the nipple before a feed and wipe residue with warm water if used near the areola.

Calculate RID

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Label mentions30 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

Moderateantiarrhythmicsclass named in the label
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
Moderatebeta blockersclass named in the label
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
ModerateDextromethorphan
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
ModerateFlecainide
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
ModerateMAO inhibitorsclass named in the label
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
ModeratePropafenone
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
ModerateSSRIs/SNRIsclass named in the label
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
Moderatetricyclic antidepressantsclass named in the label
«Drug-Drug Interactions: In vivo studies have shown that terbinafine is an inhibitor of the CYP450 2D6 isozyme. Drugs predominantly metabolized by the CYP450 2D6 isozyme include the following drug…»
FDA, section 7 · Open on DailyMed
Amiodarone
«Drug-Drug Interactions: Coadministration of a single dose of fluconazole (100 mg) with a single dose of terbinafine resulted in a 52% and 69% increase in terbinafine C max and AUC, respectively…»
FDA, section 7 · Open on DailyMed
Caffeine
«DRUG INTERACTIONS: Terbinafine is an inhibitor of CYP450 2D6 isozyme and has an effect on metabolism of desipramine. Drug interactions have also been noted with cimetidine, fluconazole, cyclosporine…»
FDA, section 7 · Open on DailyMed
calcium channel blockersclass named in the label
«Drug-Drug Interactions: Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected…»
FDA, section 7 · Open on DailyMed
Cisapride
«Drug-Drug Interactions: In vitro studies with human liver microsomes showed that terbinafine does not inhibit the metabolism of tolbutamide, ethinylestradiol, ethoxycoumarin, cyclosporine, cisapride…»
FDA, section 7 · Open on DailyMed
Digoxin
«Drug-Drug Interactions: In vitro studies with human liver microsomes showed that terbinafine does not inhibit the metabolism of tolbutamide, ethinylestradiol, ethoxycoumarin, cyclosporine, cisapride…»
FDA, section 7 · Open on DailyMed
diureticsclass named in the label
«Drug-Drug Interactions: Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected…»
FDA, section 7 · Open on DailyMed
Ethinylestradiol
«Drug-Drug Interactions: In vitro studies with human liver microsomes showed that terbinafine does not inhibit the metabolism of tolbutamide, ethinylestradiol, ethoxycoumarin, cyclosporine, cisapride…»
FDA, section 7 · Open on DailyMed
Fluvastatin
«Drug-Drug Interactions: In vitro studies with human liver microsomes showed that terbinafine does not inhibit the metabolism of tolbutamide, ethinylestradiol, ethoxycoumarin, cyclosporine, cisapride…»
FDA, section 7 · Open on DailyMed
hormonal contraceptivesclass named in the label
«Drug-Drug Interactions: Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected…»
FDA, section 7 · Open on DailyMed
Ketoconazole
«Drug-Drug Interactions: Coadministration of a single dose of fluconazole (100 mg) with a single dose of terbinafine resulted in a 52% and 69% increase in terbinafine C max and AUC, respectively…»
FDA, section 7 · Open on DailyMed
Phenytoin
«Drug-Drug Interactions: Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected…»
FDA, section 7 · Open on DailyMed
thiazide diureticsclass named in the label
«Drug-Drug Interactions: Terbinafine clearance is increased 100% by rifampin, a CYP450 enzyme inducer, and decreased 33% by cimetidine, a CYP450 enzyme inhibitor. Terbinafine clearance is unaffected…»
FDA, section 7 · Open on DailyMed
Warfarin
«Drug-Drug Interactions: There have been spontaneous reports of increase or decrease in prothrombin times in patients concomitantly taking oral terbinafine and warfarin, however, a causal relationship…»
FDA, section 7 · Open on DailyMed

From other drugs’ labels

ModerateAmitriptyline
«Potencial de otros medicamentos para afectar a la amitriptilina: Otros inhibidores del citocromo P450 : La cimetidina, el metilfenidato y los antagonistas de los canales del calcio (p. ej…»
AEMPS, section 4.5 · Open on CIMA
ModerateClozapine
«Potential for Other Drugs to Affect Clozapine: Concomitant treatment with clozapine and CYP2D6 or CYP3A4 inhibitors (e.g., cimetidine, escitalopram, erythromycin, paroxetine, bupropion, fluoxetine…»
FDA, section 7 · Open on DailyMed
ModerateDextromethorphan
«- Inhibidores de CYP2D6: El dextrometorfano se metaboliza por el CYP2D6 y tiene un elevado metabolismo de primer paso. El uso concomitante de inhibidores potentes de la enzima CYP2D6 puede aumentar…»
AEMPS, section 4.5 · Open on CIMA
ModerateMetoprolol
«Metoprolol es un sustrato del CYP2D6. Los fármacos que inhiben el CYP2D6 pueden tener un efecto en la concentración plasmática de metoprolol. Ejemplos de fármacos que inhiben CYP2D6 son quinidina…»
AEMPS, section 4.5 · Open on CIMA
ModerateTamsulosin
«DRUG INTERACTIONS: • Tamsulosin hydrochloride capsules 0.4 mg should not be used with strong inhibitors of CYP3A4 (e.g., ketoconazole). Tamsulosin hydrochloride capsules should be used with caution…»
FDA, section 7 · Open on DailyMed
Atomoxetine
«Inhibidores CYP2D6 (ISRS (p. ej. fluoxetina, paroxetina), quinidina, terbinafina)»
AEMPS, section 4.5 · Open on CIMA
Ciclosporin
«Fármacos que disminuyen los niveles de ciclosporina: Barbitúricos, carbamazepina, oxcarbazepina, fenitoina; nafcilina, sulfadimidina intravenosa; probucol; orlistat, Hypericum perforatum (hierba de…»
AEMPS, section 4.5 · Open on CIMA
Flecainide
«Antifúngicos : Terbinafina puede aumentar las concentraciones plasmáticas de flecainida como resultado de su inhibición de la actividad de CYP2D6.»
AEMPS, section 4.5 · Open on CIMA
Warfarin
«CYP450 Interactions: CYP1A2 acyclovir, allopurinol, caffeine, cimetidine, ciprofloxacin, disulfiram, enoxacin, famotidine, fluvoxamine, methoxsalen, mexiletine, norfloxacin, oral contraceptives…»
FDA, section 7 · Open on DailyMed

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Frequently asked

What is Terbinafine used for?

Terbinafine is evaluated for the following indications with varying evidence strength: Onychomycosis (evidence tier A), Superficial fungal infections (evidence tier A). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Terbinafine?

Common side effects of Terbinafine (≥ 1 in 100): Dyspepsia, nausea, diarrhoea, Headache, Skin rash and pruritus, Taste disturbance or loss (may persist for weeks after discontinuation), Asymptomatic ALT and AST elevation. See the Safety section for uncommon and serious reactions.

Is Terbinafine safe during pregnancy?

Is Terbinafine compatible with breastfeeding?

Who should not take Terbinafine?

Terbinafine is contraindicated in: Hypersensitivity to terbinafine; Active liver disease or ALT/AST more than 3× upper limit of normal; Severe renal impairment (CrCl below 50 mL/min) for systemic forms; Children under 2 years of age. Full list in the Safety section.

Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMALabel dated 05/20/2024
FDA / DailyMedLabel dated 09/19/2025

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