Find My Cancer Drug

Q R S T V X Y Z #

Fluorouracil Topical (5-FU, Carac®, Efudex®, Fluoroplex)

OncoLink Team
Last Modified: November 2, 2015

Pronounced: FLURE-oh-UE-ra-sil
Classification: Antimetabolite

About Fluorouracil

Fluorouracil (5-FU) is a type of chemotherapy that exerts its anti-cancer effect by preventing the production of DNA in the cell. Lack of functional DNA prevents the cancer cell from reproducing and making vital proteins, which then results in death of the cell.

Topical fluorouracil is used to treat actinic keratosis and superficial basal and squamous cell skin cancers. The medication destroys sun damaged skin cells, but can also damage normal skin it comes into contact with, or cause skin irritation.

How to Use Topical Fluorouracil

Topical fluorouracil (5-FU) comes as a topical cream, available in 2 strengths. Your healthcare provider will determine which strength is right for your condition and tell you how often to use the cream (typically 1-2 times a day). Most patients will use the cream for 2-12 weeks, depending on the condition being treated and the response to treatment.

To apply the cream:

  • Wash the area to be treated with plain water and dry.
  • Wear a glove when applying the medication or use a non-metal applicator to apply.
  • If your hands come into contact with the 5-FU, wash them right away.
  • Use an amount sufficient to cover the lesions being treated.
  • If you need to cover the area, use only porous gauze dressing that allows the area to "breathe".

Possible Side Effects of Topical Fluorouracil

There are a number of things you can do to manage the side effects of fluorouracil topical. Talk to your doctor or nurse about these recommendations. They can help you decide what will work best for you. These are some of the most common side effects:

Skin Changes

The treatment area will typically have a burning sensation and, after several days of treatment, become red and crusted. The area will look worse than before treatment, which will likely continue for a few weeks after treatment stops. You may experience any of the following in the treated area: darkening of skin color, pain, irritation, redness, itching, scarring, rash, and skin ulcerations.

Sun Sensitivity

This medication can make your skin more sensitive to the sun, which can result in severe sunburn or rash. Sun sensitivity can last even after chemotherapy is completed. Avoid the sun between 10-2pm, when it is strongest. Wear sunscreen (at least SPF 15) everyday; wear sunglasses, a hat and long sleeves/pants to protect your skin and seek out shade whenever possible.

Other Side Effects

The amount of medication that is absorbed into your blood is limited with topical use, but some people have a deficiency of the enzyme (DPD) needed to break down 5-FU. These patients can develop serious toxicity. If you experience diarrhea or sores in your mouth, report this to your healthcare provider right away.

Reproductive Concerns

Exposure of an unborn child to this medication could cause birth defects, so you should not become pregnant or father a child while on this medication. Effective birth control is necessary during treatment. Even if your menstrual cycle stops or you believe you are not producing sperm, you could still be fertile and conceive.  You should consult with your healthcare team before breastfeeding while receiving this medication.



If you have questions or concerns about the medication that you have been prescribed, please contact your healthcare team. OncoLink is designed for educational purposes only and is not engaged in rendering medical advice or professional services. The information provided through OncoLink should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you have or suspect you may have a health problem, you should consult your health care provider.


Click on any of these terms for more related articles


Take My Skin Cancer Prevention Challenge
by Carolyn Vachani, MSN, RN, AOCN
May 06, 2015

7 Tips for Giving Smart on #givingtuesday
by Christina Bach, MSW, LCSW, OSW-C
November 25, 2015