Terbinafine: Fast Guide to Uses, Doses, and Safety

Terbinafine is an antifungal used for skin and nail infections. You’ll see it as a cream or an oral pill. Topical terbinafine treats athlete’s foot, ringworm, and jock itch. Oral terbinafine is the go‑to for fungal nail infections because it reaches the nail bed.

How quick is it? Topical creams often clear skin infections in 1–4 weeks. Nail infections take longer: fingernails usually need about 6 weeks of pills, toenails about 12 weeks, and visible improvement can keep happening for months after treatment ends.

Dosage & treatment length

For skin infections, topical terbinafine is usually applied once or twice daily as directed on the package. For nail infections, the common oral dose is 250 mg once daily. Typical courses are 6 weeks for fingernail infections and 12 weeks for toenail infections. Don’t stop early just because the nail looks better—you need to finish the full course for the fungus to clear.

Side effects, safety, and interactions

Most people tolerate terbinafine well. Common side effects are stomach upset, headache, and changes in taste. A lost or altered sense of taste can be especially troubling; tell your doctor if that happens. Rare but serious issues include liver injury and severe skin reactions. If you develop jaundice, dark urine, or a rash that spreads or blisters, stop the drug and seek medical help immediately.

Before you take oral terbinafine, check liver health. Your doctor may order blood tests (LFTs) before starting and during treatment if you have liver disease, drink heavily, or take other risky drugs. Terbinafine can affect CYP2D6 enzymes, so it may interact with some antidepressants, certain heart medicines, and tamoxifen. If you take blood thinners like warfarin, your provider will monitor you more closely.

Pregnancy and breastfeeding are special cases. Topical terbinafine is generally low risk, but oral terbinafine is usually avoided in pregnancy. Talk with your clinician if you’re pregnant, planning pregnancy, or breastfeeding.

Want better results? Keep the infected area clean and dry, trim nails short, and use antifungal nail files or debridement if recommended. For athletes, change socks daily and use breathable shoes. Prevent re‑infection by treating skin infections early—untreated skin fungus can spread back to nails.

If oral terbinafine isn’t effective or you can’t take it, alternatives include oral itraconazole and medicated nail lacquers such as ciclopirox. Those options have different side effect profiles and monitoring needs, so compare them with your doctor.

Some people combine oral and topical treatments for faster results—ask your doctor if that makes sense for you. Expect the nail to look worse before it gets better; growth is slow. Follow up after treatment so your clinician can confirm the infection is gone and advise on steps to avoid recurrence, like treating contacts.

When to see a doctor: persistent or worsening infection, signs of liver problems, allergic rash, or new symptoms while on the drug. Proper use and a quick check with your clinician give you the best shot at clearing a stubborn fungal infection.