5-Fluorouracil (Efudix)

What is 5-FU and how does it work?

5-FU cream is a treatment which destroys sun-damaged cells in the skin by blocking an enzyme called thymidylate synthetase that is highly active in these cells, thus causing their death and sparing the normal cells. It has been in use for about 50 years.

In the UK, a 5% 5-FU cream is available (trade name Efudix®), but other formulations are on the market in other countries.

What skin conditions are treated with 5-FU cream?

5-FU cream is licensed for the use of sun-damage in the form of superficial pre-cancerous and cancerous skin conditions, such as actinic keratoses, Bowen’s disease or superficial basal cell carcinoma. It is also sometimes used for other, non-licensed indications, for example viral warts.


Will 5-FU cream cure my skin condition?

Depending on your skin complaint, 5-FU cream may cure or improve it, but it does not work for everybody. If you have more severe sun-damage, you may require repeated treatment courses in the future to maintain the improvement.


How often should I use 5-FU cream?

How often or for how long you should use 5-FU cream will depend on your skin condition and other factors, for example which part of your skin is affected or if you also have another skin complaint such as eczema. 5-FU cream can for example be applied once or twice a day, for 3 weeks or longer. Your doctor will recommend a treatment schedule to you.

If you have widespread sun-damage, then the treatment area should be broken up into smaller areas, and treated in a piecemeal fashion.


What time of day should I apply 5-FU cream?

If you are asked by your doctor to use 5-FU cream once a day, you should apply it at night: if twice daily, morning and night. Make sure you always clean your skin prior to the application of the cream.

After 20 minutes or so, you may then apply an additional moisturizer. You can also use make-up to cover the redness, but you may find this uncomfortable.

Only cover 5-FU cream with a plaster if advised by your doctor, otherwise leave the treated area open.

You should wash your hands thoroughly after application of the cream.


When should I not apply 5-FU cream?

5-FU cream should not be used on the eyelids, and not on the lips, unless specifically prescribed by your doctor for use in that area.

Do not use 5-FU cream if you are allergic to any ingredients, for example parabens.

Do not apply 5-FU cream if you are pregnant or breastfeeding.


What are the common side effects of 5-FU cream?

Within 3-5 days, skin treated with 5-FU cream usually becomes inflamed, and can get intensely red and sore. Even normal looking skin may be affected, because the cream also treats abnormal cells where the sun-damage is not yet visible. The skin may weep, peel, crack or even blister. This is a normal response to 5-FU. If the skin becomes very sore or uncomfortable please stop using the Efudix cream temporarily. Bathe the area with water, then dry and apply Vaseline daily to settle the skin. Once the skin has settled you can re-start using the Efudix cream as directed. Your doctor may prescribe a steroid cream to settle the inflammation. Whilst the skin is inflamed, there is a risk that it might become infected, and if you have any concerns regarding this you should consult your doctor.

5-FU cream makes your skin more sensitive to light, and therefore you should protect your skin during and for a while after treatment.


What are the rare side effects of 5-FU cream?

If you have a severe reaction to 5-FU cream, the treated area may become ulcerated. This risk is highest on the legs.

Following a severe reaction, there is a small risk of scarring.

Rarely, patients can be allergic to 5-FU cream and develop a severe allergic skin rash.


Where can I get more information about 5-FU cream?

Links to patient support groups: