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Fluorouracil (5-FU) for Nonmelanoma Skin Cancer


Generic NameBrand Name
fluorouracil (5-FU)Carac, Efudex, Fluoroplex

How It Works

Fluorouracil (5-FU) is an anticancer medicine that works by slowing or stopping cell growth. The medicine 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 superficial (only in the top layer of skin). It can also be used to treat some squamous cell carcinomas in the eye.1

How Well It Works

This medicine works well for treating superficial actinic keratosis.2 If you have superficial basal cell carcinoma or squamous cell carcinoma in situ and surgery is not possible, your doctor may suggest treatment with 5-FU cream.

Studies show a clearance rate of 90% when 5-FU cream is used to treat superficial basal cell carcinoma and 27% to 85% when this cream is used to treat squamous cell carcinoma in situ.3 Treatment with 5-FU does not usually cause scarring.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Callor other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.

Stop using this medicine and call your doctor right away if you have:

Common side effects of this medicine include:

  • Redness and dryness.
  • Burning and pain.
  • Loss of the upper layer of skin.
  • Swelling.

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

What To Think About

Applying 5-FU on skin almost always causes pain and a burning feeling. This may make it hard to tell if you are having an allergic reaction to the medicine or if the medicine is working as expected.

Your skin may be sensitive to sunlight during your treatment with 5-FU. So you will need to protect your skin from the sun.

People treated with 5-FU will need to have regular follow-up visits with their doctors to make sure the skin cancer is gone.

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

Do not use this medicine if you are pregnant, breast-feeding, or planning to get pregnant. If you need to use this medicine, talk to your doctor about how you can prevent pregnancy.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

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



  1. Grossman D, Leffell DJ (2012). Squamous cell carcinoma. In LA Goldman et al., eds., Fitzpatrick's Dermatology in General Medicine, 8th ed., vol. 1, pp. 1283–1294. New York: McGraw-Hill.

  2. Habif TP (2010). Premalignant and malignant nonmelanoma skin tumors. In Clinical Dermatology: A Color Guide to Diagnosis and Therapy, 5th ed., pp. 801–846. Edinburgh: Mosby Elsevier.

  3. Love WE, et al. (2009). Topical imiquimod or fluorouracil therapy for basal and squamous cell carcinoma: A systematic review. Archives of Dermatology, 145(12): 1431–1438.


ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerAmy McMichael, MD - Dermatology
Last RevisedOctober 2, 2012

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