Terbinafine

What is terbinafine?

Terbinafine is an antifungal medicine used to treat fungal infections by killing fungi and yeasts. It is available as tablets, creams, gels and sprays. The tablets are prescription only, but the creams, gels and sprays can be purchased over the counter under brand names such as Lamisil and Lamisil Once[1]. 

What is terbinafine used to treat?

Terbinafine is commonly used to treat[1]: 

• Athlete’s foot (tinea pedis) 

• Fungal nail infections (onychomycosis) 

• Jock itch (tinea cruris) 

• Ringworm (tinea corporis) 

• Other fungal and candidal skin infections 

How does terbinafine work?

Terbinafine blocks an enzyme called squalene epoxidase, which fungi need to build their cell membranes. This causes toxic substances to build up inside the fungus, killing it[1].  

Who can take terbinafine?

Most adults and children over 1 year old can take terbinafine. Avoid or consult a doctor if you[1]: 

• Have liver or kidney problems 

• Have psoriasis or lupus 

• Are pregnant or breastfeeding 

• Are taking certain medications (see below) 

If buying over the counter then use is restricted to 16 years old and over for the creams, gels, and sprays and 18 years old and over for the solution. 

What is the typical dose of terbinafine and how do you take it?

The usual dose of terbinafine tablets is 250mg once daily. The duration of  your course varies based on the type of infection[1]:  

• Skin infections: 2 to 6 weeks 

• Nail infections: 6 weeks to 3 months or longer 

The cream, gel or spray is used once or twice daily for 1-2 weeks. Consult a doctor after this period if the infection is unresolved. The solution which is called Lamisil Once is only used a single time[1]. 

Always complete the full course as prescribed even if you feel better or the infection seems to have resolved. Completing the course helps to prevent it from reoccurring.. 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

Can you suddenly stop taking terbinafine?

No, you should complete the full course even if symptoms improve to prevent the infection returning. Always complete the prescribed course unless advised otherwise by your doctor[1]. 

What do you do if you forget a dose of terbinafine?

For the cream, gel or spray use it as soon as you remember and then continue with the usual routine. For the tablets take it as soon as you remember unless it is nearly time for your next dose. If this is the case skip the missed dose and continue from the next dose as usual. Do not take two doses at once[1]. 

Medicines to avoid with terbinafine

When used as a cream, gel, spray or solution interactions with other medications are unlikely. For the tablets, interactions may occur with[1]: 

• Antidepressants (e.g., fluoxetine, amitriptyline) 

• Beta-blockers (e.g., propranolol) 

• Cimetidine (ulcer treatment) 

• Rifampicin (antibiotic) 

• Oral contraception 

• Amiodarone 

• Ciclosporin 

• Tamoxifen 

• Warfarin 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of terbinafine?

The most common side effects of the cream, gel spray and solution is peeling or itching skin. If this occurs try using a thinner layer of the product or stopping completely if irritation persists. The most common side effects of the tablets include[1]: 

• Headache 

• Diarrhoea 

• Indigestion or stomachache 

• Rash 

• Muscle or joint pain 

• Nausea and vomiting 

• Reduction in appetite 

• Dizziness 

• Loss of taste 

• Vision problems 

The rarer, but more serious side effects include[1]: 

• Liver problems (yellow skin/eyes, dark urine) 

• Severe skin reactions 

• Severe stomach pain spreading to the back which may indicate pancreatitis 

• Unexplained bruising or recurrent infections which may indicate blood disorders 

• Weak, painful muscles with dark red or brown urine 

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include:

• Difficulty breathing

• Tightness in throat and chest

• Swelling of the tongue or throat

• Feeling faint or dizzy

• Blue/grey skin or lips

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about terbinafine

Can I drink alcohol with terbinafine? 
Yes but avoid excessive drinking as both alcohol and terbinafine can affect the liver[1]. 

Can I drive or cycle on terbinafine? 
Terbinafine can cause dizziness, tiredness or make you feel unwell. If this happens do not drive or cycle until you feel better[1]. 

Can I use terbinafine long-term? 
There is a small risk of liver problems when used long term so you will be monitored carefully if this is necessary[1]. 

Is terbinafine safe during pregnancy? 
There is a small risk of liver problems when used long term so you will be monitored carefully if this is necessary[1]. 

How does terbinafine affect oral contraception?  

It is not likely to affect oral contraception, however, there have been reports of breakthrough bleeding when the combined oral contraceptive is used with terbinafine. If you experience this speak to your doctor about your options. If terbinafine causes vomiting or diarrhoea, then it may affect oral contraception, and you should follow missed pill instructions in your contraceptive patient information leaflet[1][2]. 

For the official NHS guide for terbinafine, visit their website.