An allylamine antifungal that is the treatment of choice for dermatophyte infections (onychomycosis, tinea capitis). Highly effective against Trichophyton, Microsporum, and Epidermophyton species. Oral terbinafine is the most effective treatment for toenail onychomycosis with cure rates of 70-80%. Also available topically for tinea pedis, tinea corporis, and tinea cruris.
Evidence rating strong. Most-documented uses: first-line treatment for toenail onychomycosis, treats fingernail onychomycosis, treats tinea capitis (oral). 10 sources indexed (2011–2025), with 3 interaction records on file.
The science
How it works, mechanistically.
Core mechanism
Inhibits squalene epoxidase, a key enzyme in the fungal ergosterol biosynthetic pathway. This enzyme converts squalene to squalene-2,3-epoxide, an early step in ergosterol synthesis. Inhibition leads to squalene accumulation (which is directly toxic to fungal cells) and ergosterol depletion (which destabilizes the cell membrane). The dual mechanism makes terbinafine fungicidal against dermatophytes, unlike azoles which are primarily fungistatic.
Class
Allylamine Antifungal
Absorption
Fat-soluble; take with food
Dosing
Dosing & protocol.
Common range
250 mg once daily; toenail onychomycosis: 12 weeks; fingernail onychomycosis: 6 weeks; tinea capitis: 4-6 weeks (as prescribed by your physician)
Recommended form
Oral tablets; also available as topical cream, gel, or spray
Well absorbed orally (>70% bioavailability). Food slightly increases absorption but not clinically significant. Highly lipophilic, concentrates in skin, nails, and adipose tissue. Persists in nail tissue for months after discontinuation.
Safety
Full safety detail.
Side effects
Headache
Diarrhea
Dyspepsia and abdominal pain
Taste disturbance or loss (dysgeusia/ageusia)
Elevated liver enzymes (hepatotoxicity, including rare liver failure)
Terbinafine is associated with idiosyncratic hepatotoxicity, including cholestatic hepatitis and rare cases of liver failure requiring transplant. Alcohol is a leading risk factor for drug-induced liver injury and meaningfully increases the chance of symptomatic liver injury during the typical 6-12 week onychomycosis course.
Recommendation: Avoid alcohol throughout the terbinafine course and for at least a few days after it ends. Report any nausea, dark urine, abdominal pain, or yellowing of skin or eyes immediately.
Terbinafine is metabolized to a reactive allylic aldehyde (TBF-A) thought to drive its idiosyncratic hepatotoxicity. N-acetylcysteine restores glutathione and has been used in non-acetaminophen drug-induced liver injury. The combination is not a proven prophylactic but is a low-risk adjunct in higher-risk patients on multi-month courses.
Recommendation: Do not rely on NAC instead of routine liver enzyme monitoring. If you have additional hepatotoxicity risk factors, discuss adjunctive NAC with your prescriber.
Oral terbinafine treats fungal infections but its mycobiome and microbiome impact in humans is incompletely characterized, and antifungal exposure in animal models alters fungal and bacterial gut communities. Probiotic strains such as Lactobacillus and Saccharomyces boulardii have anti-Candida and barrier-supportive effects that may help restore balance after a long oral antifungal course.
Recommendation: If you want to use probiotics during or after a terbinafine course, choose a well-studied strain. Take Saccharomyces boulardii only after the antifungal course is complete, since terbinafine has limited activity against yeasts and S. boulardii is itself a yeast.
Ferreira CB, Lisboa C. A systematic review on the emergence of terbinafine-resistant Trichophyton indotineae in Europe: Time to act?. Journal of the European Academy of Dermatology and Venereology : JEADV. 2025
Jegathees T, Holmes ZP, Martin C et al.. Emerging Terbinafine Resistant Trichophyton Dermatophytosis, Testing Options and Alternative Treatments: A Systematic Review. The Australasian journal of dermatology. 2025
Yin Z, Xu J, Luo D. A meta-analysis comparing long-term recurrences of toenail onychomycosis after successful treatment with terbinafine versus itraconazole. The Journal of dermatological treatment. 2012
Tey HL, Tan AS, Chan YC. Meta-analysis of randomized, controlled trials comparing griseofulvin and terbinafine in the treatment of tinea capitis. Journal of the American Academy of Dermatology. 2011
This page is educational. Do not start, stop, or change a supplement or medication based on it without checking with a qualified healthcare professional.
Use this with your stack
Terbinafine in NutriStack.
Add it to your stack, see how it interacts with everything else you take, and get a Stack Score that updates the moment it does.
NutriStack is an informational and organizational tool, not a medical service, and not a substitute for professional advice. Always consult a qualified healthcare professional before starting, stopping, or changing any supplement or medication.
NutriStack