Efudex Dangers

Updated February 21, 2017

The prescription topical medication Efudex contains fluorouracil, a chemotherapy drug used to destroy cancerous cells. Doctors prescribe Efudex for the treatment of both skin cancer and skin abnormalities that have the potential to develop into cancer later in life. The medication works by preventing cancer cells from reproducing their DNA. Despite its effectiveness, Efudex poses a risk for side effects in some patients.

Skin Reactions

The most common side effects of Efudex affect the skin and include burning, itching, oozing, tenderness and discolouration. While unpleasant, these side effects rarely pose any threat for long-term health complications and may diminish as your body becomes acclimated to the effects of the medication, explains the Mayo Clinic. Infrequently, Efudex causes ulceration or sores to form on your skin.


Efudex has the potential to increase your photosensitivity, making your skin more sensitive to sunlight. Because this poses a risk for severe sunburns, take necessary precautions to protect your skin throughout your treatment for the first two months after you finish using Efudex, suggests the Mayo Clinic. Avoid tanning and, when possible, stay out of the sun from 10:00 a.m. to 3:00 p.m., as the sun's rays are strongest during this time of day. Wearing protective clothing, such as a wide-brimmed hat, and using sunscreen with at least SPF 15 are also important steps to take to protect your skin during Efudex treatment.

Mucous Membranes and Eyes

Efudex may cause ulceration or severe inflammation if the medication comes in contact with your eyes or the mucous membranes inside of your nose or around your mouth, cautions RxList. Wash your hands carefully after applying the cream to avoid accidentally contaminating areas of your face. Even if the medication does not come in contact with your eyes, you may notice that your eyes water more while you are undergoing Efudex treatment. Typically, this does not indicate any type of serious reaction unless accompanied by redness or irritation.


Infrequenty, the use of Efudex leads to change in the counts of certain blood cells, reports RxList. The most common of these hematological effects is leukocytosis, an elevated level of certain white blood cells that is unlikely to produce any noticeable symptoms. A more serious, but rarer complication of Efudex use is thrombocytopenia, a shortage of the blood platelets that are vital for blood clotting. Signs of thrombocytopenia include easy bruising, nosebleeds or tiny red pin-prick-type dots on your skin. If left untreated thrombocytopenia has the potential to cause bleeding in your brain or digestive system, warns the U.S. National Library of Medicine.


Efudex is known to cause birth defects, such as cleft palates in infants whose mothers were treated with the drug. Fluorouracil has also been linked to miscarriages in some women. Because of this, doctors avoid prescribing the drug for use in pregnant women, reports RxList.


Patients with dihydropyrimidine dehydrogenase enzyme deficiencies (DPD) may experience toxic side effects if treated with Efudex, including stomach inflammation, abdominal pain, bloody diarrhoea, vomiting, fever and chills. If you have any other skin conditions, such as psoriasis, eczema or rosacea, Efudex may make your skin problem worse, cautions the Mayo Clinic.

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About the Author

Faith Davies has been writing professionally since 1996, contributing to various websites. She holds an LAH insurance license in the state of Pennsylvania and has experience as a bank branch manager and lending officer. Davies graduated cum laude from the University of Pittsburgh with a Bachelor of Arts in art history.