Does Efudex (topical fluorouracil) cause side effects?

Efudex (topical fluorouracil) is contains an antineoplastic antimetabolite used to treat conditions of the skin in which there is rapid multiplication (division) of cells, for example, skin cancer or precancerous conditions including solar keratoses, actinic keratosis, superficial basal cell carcinoma, and Bowen's disease (a type of skin cancer).

It also is used to treat some noncancerous conditions in which cells are dividing rapidly, including psoriasis, genital warts, and porokeratosis (an unusual inherited skin condition causing dry patches on the arms and legs). 

Efudex works best on the face and scalp, and is less effective on other areas of the body. It also destroys sun-damaged skin cells making the skin smoother and more youthful-appearing. 

In order to multiply or divide, cells must produce DNA for each new cell. The DNA is critical since it is the genetic material that directs the activity of all cells. Production of DNA depends on the production of RNA which serves as a messenger during the production of DNA. 

Efudex prevents the formation of RNA which, in turn, prevents the formation of DNA. As a result, cells cannot multiply. With continued treatment, the remaining cells also die.

Common side effects of Efudex include

  • stinging,
  • burning sensation,
  • irritation,
  • sun sensitivity,
  • pain,
  • itching,
  • swelling,
  • allergic reactions, and
  • redness.

Serious side effects of Efudex include

  • ulcer formation,
  • loss of pigmentation (hypopigmentation),
  • scarring, and
  • bacterial infection.

There are no known drug interactions with topical Efudex. Although very little fluorouracil is absorbed from normal skin, about 20% can be absorbed into the blood when fluorouracil is applied to damaged skin. 

Efudex can cause damage to the fetus, and it should not be used by pregnant women. 

It is unknown if Efudex passes into breast milk. Since some amount is absorbed from the skin into the body, breastfeeding mothers should not use Efudex.

What are the important side effects of Efudex (topical fluorouracil)?

Common side effects of topical fluorouracil include:

  • Stinging
  • Burning sensation
  • Irritation
  • Sun sensitivity
  • Pain
  • Itching
  • Swelling
  • Allergic reactions
  • Redness

Other side effects include:

  • Ulcer formation
  • Hypo-pigmentation
  • Scarring
  • Bacterial infection

Efudex (topical fluorouracil) side effects list for healthcare professionals

The most frequent adverse reactions to Efudex occur locally and are often related to an extension of the pharmacological activity of the drug.

These reactions include:

Ulcerations, other local reactions, cases of miscarriage and a birth defect (ventricular septal defect) have been reported when Efudex was applied to mucous membrane areas. Leukocytosis is the most frequent hematological side effect.

Although a causal relationship is remote, other adverse reactions which have been reported infrequently are:

To report SUSPECTED ADVERSE REACTIONS, contact Valeant Pharmaceuticals North America LLC at 1-800-321-4576 and/or FDA at 1-800-FDA-1088 or

What drugs interact with Efudex (topical fluorouracil)?

No information provided.

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Medically Reviewed on 11/20/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.