Fluorouracil (5-FU) for nonmelanoma skin cancer


Generic Name Brand Name
fluorouracil (5-FU) Carac, Efudex

How It Works

Fluorouracil (5-FU) is an anticancer medication that works by slowing or stopping cell growth. The medication interferes with the ability of abnormal cells to grow on the skin's top layer.

5-FU is usually applied once or twice daily for several weeks. It works by causing a painful irritation in actinic keratosis or a skin cancer. Successful treatment results in the specific areas of diseased skin becoming inflamed and crusting as the abnormal cells die.

Why It Is Used

5-FU cream or solution is used to treat actinic keratosis and basal cell carcinomas that are limited to the top layer of skin (epidermis). It can also be used to treat some squamous cell carcinomas in the eye.1

How Well It Works

Cure rates for treatment for actinic keratosis are 93% when the treatment is completed. But cure rates can be as low as 40% if the medicine is not used as the doctor directs.2 5-FU treatment does not usually cause scarring.

Side Effects

Side effects from fluorouracil (5-FU) treatment are common and include:

It is expected that people receiving 5-FU treatment will experience pain and burning while the medication works to destroy the skin disease. It may be difficult to tell the difference between the expected action of 5-FU on your skin and an allergic reaction.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

5-FU treatment does not affect growths underneath the surface of the skin, so follow-up examinations are needed to detect deeper cancer.

Sunlight on the treated area can cause intense pain, so protection from sun exposure is needed during treatment.2

To reduce side effects and the risk of an allergic reaction and have the greatest chance of a cure, 5-FU should only be applied as directed by your doctor.2

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.



  1. Grossman D, Leffell DJ (2008). Squamous cell carcinoma. In K Wolff et al., eds., Fitzpatrick's Dermatology in General Medicine, 7th ed., vol. 1, pp. 1028–1036. New York: McGraw-Hill Medical.
  2. Dinehart SM (2000). The treatment of actinic keratoses. Journal of American Academy of Dermatology, 42: S25–S28.

Last Updated: October 14, 2008

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