An antifungal for skin and nail infections
Terbinafine
The usual treatment for stubborn fungal nail and skin infections — taken as a tablet for weeks to months, or applied as a cream for milder skin infections.
What is Terbinafine?
Terbinafine is an antifungal used mainly for fungal infections of the nails and skin, such as fungal nail infection, athlete’s foot and ringworm. For nails and more stubborn skin infections it is taken as a daily tablet for several weeks to months; milder skin infections are treated with a cream. Tablets need occasional liver monitoring and can rarely disturb taste.
Education and reference only. This is a plain-language guide to Terbinafine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Terbinafine is a very effective antifungal medicine, best known for treating fungal nail infections and ringworm-type skin infections (including athlete’s foot and jock itch). It comes as a tablet for infections that need treating from the inside — particularly nails, which take a long course — and as a cream for milder skin infections. It is especially good against the dermatophyte fungi that cause these infections. The tablet course can be long (weeks for skin, months for nails) because nails grow slowly.
How it works
Terbinafine blocks an enzyme (squalene epoxidase) that fungi need to make ergosterol, an essential building block of their cell membrane. Without it, a toxic substance builds up inside the fungus and its membrane fails, killing it. It concentrates well in skin, nails and hair, which is why it is so effective for these infections — and why nail treatment works even though the course finishes long before the healthy nail has fully grown out.
What it treats
Conditions Terbinafine is used for
Practical use
How to take Terbinafine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- For nails or stubborn skin infections, take the tablet once daily for the full course — often 6 weeks for fingernails and 3 months or more for toenails.
- Expect the nail to keep improving for months after the course ends, as the new healthy nail grows out.
- Report yellowing of the skin or eyes, dark urine, persistent nausea, or a marked change in taste.
- For the cream, apply as directed to the affected skin (and a margin around it) and complete the course even once it looks better.
- Attend any liver blood tests requested before or during tablet treatment.
Weighing it up
Advantages & disadvantages of Terbinafine
Advantages
- Highly effective against the fungi that cause nail and ringworm-type skin infections.
- Concentrates in nails and skin, so it keeps working after the course ends.
- Available as both tablets (for nails/stubborn infections) and a very safe cream (for milder skin infections).
Disadvantages
- Nail courses are long (months) and results appear slowly.
- Tablets can rarely affect the liver and need monitoring; can disturb taste.
- Interacts with a few medicines (such as some antidepressants and beta-blockers) via a liver enzyme.
Practical use
Good to know
For nail infections, terbinafine tablets are usually taken daily for around six weeks (fingernails) to three months or more (toenails) — and the nail continues to improve in appearance for months after the course finishes, as the healthy nail grows out, so don’t expect an instant change. Tablets are generally well tolerated but can occasionally affect the liver, so liver blood tests are checked before and sometimes during treatment; report yellowing of the skin or eyes, dark urine, or persistent nausea. A temporary loss or distortion of taste can occur and usually recovers after stopping. The cream is very safe and used for milder skin infections.
Who should not take it / use with caution
- People with significant liver disease should generally avoid the tablets.
- Used with care in significant kidney impairment and in certain skin conditions (it can occasionally trigger or worsen lupus-like reactions or psoriasis).
- Pregnancy and breastfeeding — the tablets are usually postponed, as nail infection is not urgent.
Monitoring
- Liver function before, and sometimes during, tablet treatment
- For signs of liver problems or serious skin reactions
- Response of the nail or skin over the following months
Side effects
- Common: digestive upset (nausea, fullness, diarrhoea), headache, and rash.
- A temporary reduction or distortion of taste, which usually recovers after stopping.
- Rarely, liver problems (report jaundice, dark urine, persistent nausea) or serious skin reactions.
Key interactions
- It inhibits a liver enzyme (CYP2D6), so it can raise the level of some antidepressants (such as tricyclics and some SSRIs) and certain beta-blockers.
- Rifampicin lowers terbinafine levels; cimetidine can raise them.
- Tell your prescriber your full medicine list before a tablet course.
Available as: Tablets, and a skin cream (also available as a spray or gel) for milder skin infections.
Answers
Terbinafine: frequently asked questions
How long does terbinafine take to clear a nail infection?
The tablet course is usually about 6 weeks for fingernails and 3 months or more for toenails — but the nail keeps improving for several months after the course finishes, as the healthy nail grows out. So a normal-looking nail can take up to a year, even though treatment stopped much earlier. This is expected, not a sign the treatment failed.
Do I need blood tests with terbinafine tablets?
Yes, usually — because the tablets can occasionally affect the liver, liver blood tests are checked before starting and sometimes during a long course. Report yellowing of the skin or eyes, dark urine, or persistent nausea, which can signal a liver problem.
Why has my sense of taste changed?
Terbinafine can temporarily reduce or distort taste in some people. It is not dangerous and usually recovers over weeks to months after the course finishes, though occasionally it lingers. Mention it to your prescriber if it is troubling you.
Is the cream as strong as the tablets?
The cream works well for milder skin infections such as athlete’s foot and ringworm, and it is very safe because very little enters the body. Nail infections and more widespread or stubborn skin infections usually need the tablets, which treat the fungus from the inside.
The wider class
About Systemic antifungals
Terbinafine belongs to the systemic antifungals class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
Browse by body system
Authoritative sources
- BNF: Terbinafine.
- electronic Medicines Compendium (SmPC): Terbinafine (Lamisil).
- NICE CKS: Fungal skin infection; Fungal nail infection.
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