How does Efudex work?

Efudex belongs to a group of drugs called antimetabolites. It works by targeting and killing the fast-growing cells found in actinic keratosis and basal cell carcinoma.

How long does it take for Efudex to work?

It may take two to four weeks to treat actinic keratosis and three to six weeks (but up to 12 weeks) to treat basal cell carcinoma.

Efudex (Fluorouracil) - Topical: Uses, Side Effects

What Is Efudex?

Efudex (fluorouracil) is a topical prescription cream used to treat certain forms of skin cancer and precancerous skin conditions in adults. Efudex belongs to a group of drugs called antimetabolites. It works by blocking DNA production, which kills the abnormally fast-growing cells found in skin cancer and precancerous lesions.

Drug Facts

Generic Name: Fluorouracil

Brand Name(s): Efudex

Drug Availability: Prescription

Therapeutic Classification: Antimetabolite

Available Generically: Yes

Controlled Substance: No

Administration Route: Topical

Active Ingredient: Fluorouracil

Dosage Form(s): Topical cream

What Is Efudex Used For?

Efudex is a topical cream used to treat actinic keratosis (also known as solar keratosis or sunspots) and certain forms of basal cell carcinoma (skin cancer) in adults.

Actinic keratoses are rough, scaly patches that form on the skin due to long-term exposure to ultraviolet (UV) rays from the sun or indoor tanning beds. Because these lesions can progress to skin cancer if left untreated, actinic keratosis is considered a form of precancer. Actinic keratosis is one of the most common reasons people visit a dermatologist and occurs in 37.5% of the white population.

Basal cell carcinoma (BCC) is the most common form of skin cancer, with an estimated 3.6 million cases diagnosed annually in the United States. Because BCC grows slowly, most cases are curable if caught and treated early. BCC often occurs on areas of the skin exposed to sun and may look like:

Open sores
Red patches
Pink growths
Shiny bumps
Scars or growths with raised edges or an indentation in the middle

BCC may appear brown in people with darker skin. Because BCC's appearance can vary greatly, it's essential to see your dermatologist any time you notice something new, changing, or unusual on your skin.

An illustration with drug information about Efudex (fluorouracil) — Illustration by Dennis Madamba for Verywell Health

How to Take Efudex

Efudex cream is typically applied twice daily to the affected areas of your skin. Before you apply this medication to your skin, clean the area and dry it well. It's best to apply Efudex with a nonmetal applicator or with gloves. If you apply Efudex with your fingers, wash your hands immediately after applying this medication.

Efudex should only be applied to the skin as directed by your healthcare provider. Do not apply Efudex to your eyelids, eyes, nose, or mouth. If this medication does get in these areas, rinse with plenty of water. Do not cover the application site with bandages or wraps unless your healthcare provider tells you to.

UV rays can increase the risk of side effects, so it's essential to avoid sun exposure while using Efudex.

Storage

Store Efudex at room temperature in a safe location out of the reach of children and pets. Efudex can be fatal if swallowed by pets. Do not allow pets to come into contact with the Efudex container, skin where Efudex had been applied, or any applicators that may contain Efudex residue.

Do not store your medications in the bathroom.

Off-Label Uses

Healthcare providers may prescribe medicines for conditions other than those approved by the FDA. This is called off-label use. Efudex may be used off-label to treat:

Squamous cell carcinoma (early stage)
Penile cancer (early stage)

How Long Does Efudex Take to Work?

If you're using Efudex to treat actinic keratosis, your healthcare provider will likely recommend you use Efudex until the lesions start to peel off. This typically takes two to four weeks. Your skin may not fully heal for one to two months after stopping Efudex.

For basal cell carcinoma, lesions usually take three to six weeks to clear, although up to 12 weeks of treatment may be necessary.

What Are the Side Effects of Efudex?

This is not a complete list of side effects, and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your pharmacist or a healthcare provider. You may report side effects to the FDA at www.fda.gov/medwatch or 800-FDA-1088.

Common Side Effects

During the first few weeks of treatment, the area where you apply Efudex will appear red, swollen, and scaly. Blisters may form, and the lesion will eventually peel off and heal. This is normal and is a sign that Efudex is working. Do not stop taking Efudex without talking with your healthcare provider first.

Common side effects include:

Burning
Crusting
Rash
Itching
Scarring
Soreness
Open sores

Let your healthcare provider know if you develop any side effects that bother you or don't go away.

Severe Side Effects

Rarely, Efudex may cause serious side effects. Contact your healthcare provider right away if you develop any signs of a severe reaction. Call 911 if your symptoms feel life-threatening.

Contact your healthcare provider if you notice any of the following symptoms since they may be signs of a serious reaction:

Severe stomach pain
Bloody diarrhea
Vomiting
Fevers
Chills
Severe red skin rash

Report Side Effects

Efudex may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

(800) 332-1088

Dosage: How Much Efudex Should I Take?

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

For topical dosage form (cream and solution):
- For actinic or solar keratosis:
  - Adults—Apply to the affected area 2 times a day for 2 to 4 weeks.
  - Children—Use and dose must be determined by your doctor.
- For superficial basal cell carcinomas:
  - Adults—Apply to the affected area 2 times a day for 3 to 6 weeks.
  - Children—Use and dose must be determined by your doctor.

Modifications

The following modifications (changes) should be kept in mind when using Efudex:

Severe allergic reaction: Avoid using Efudex if you have a known allergy to it or its ingredients. Ask your pharmacist or healthcare provider for a complete list of the ingredients if you're unsure.

Pregnancy: You should not use Efudex if you are pregnant or plan to become pregnant. Cases of miscarriages and birth defects have occurred in people using Efudex. Let your healthcare provider know if you are pregnant or plan to become pregnant before starting treatment with Efudex.

Breastfeeding: We don't know enough about the safety of Efudex in human breast milk and nursing babies. Talk with your healthcare provider if you plan to breastfeed about the benefits and risks of taking Efudex while nursing and the different ways to feed your baby.

Adults over 65: We don't know enough about whether people in this age group respond differently to Efudex than younger adults. Older adults may be more sensitive to Efudex's side effects.

Children: The safety and effectiveness of using Efudex in children have not been established.

Missed Dose

If you accidentally forgot your Efudex dose, apply it as soon as you remember. If it's already close to your next scheduled dose, then skip the missed dose and apply the following dose at your next scheduled dosing time. Don't try to double up to make up for the missed dose.

Try to help yourself remember to keep your appointments and take your medication routinely. If you miss too many doses, Efudex might be less effective at treating your condition.

Overdose: What Happens if I Take Too Much Efudex?

There is limited information available about the effects of an Efudex overdose.

If you think that you're experiencing an overdose or life-threatening symptoms, however, seek immediate medical attention.

What Happens if I Overdose on Efudex?

If you think you or someone else may have overdosed on Efudex, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking Efudex, call 911 immediately.

911

Precautions

It is very important that your doctor check your progress at regular visits for any unwanted effects that may be caused by this medicine.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant during treatment. If you think you have become pregnant while using the medicine, tell your doctor right away.

This medicine may make your skin more sensitive to sunlight. Wear sunscreen. Do not use sunlamps or tanning beds. If you have a severe reaction from the sun, check with your doctor.

This medicine may cause black, tarry stools, blurred or double vision, chills, cough, diarrhea, difficulty in walking, drooping eyelids, fever, headache, jaw pain, lower back or side pain, numbness or tingling in the fingers and toes, pain in the fingers, toes, and testicles, painful or difficult urination, pale skin, sore throat, sores, ulcers, or white spots in the mouth or on the lips, swelling or inflammation of the mouth, unusual bleeding or bruising, or unusual tiredness or weakness. Check with your doctor right away if you notice any of these serious side effects.

What Are Reasons I Shouldn’t Take Efudex?

Do not take Efudex if you:

Are pregnant or plan to become pregnant
Are allergic to Efudex or any of its ingredients
Have dihydropyrimidine dehydrogenase (DPD) enzyme deficiency (a condition where the body can't break down thymine or uracil)

What Other Medications Interact With Efudex?

Efudex is not expected to interact with most medicines. However, be sure to let your healthcare provider and pharmacist know about all the medicines you take, including over-the-counter, nonprescription products, vitamins, and herbal supplements.

What Medications Are Similar?

Efudex is the only topical antimetabolite medication used to treat actinic keratosis and basal cell carcinoma. Other topical therapies that work differently but also treat actinic keratosis or basal cell carcinoma include:

Imiquimod cream
Diclofenac gel
Klisyri (tirbanibulin) ointment

Frequently Asked Questions

What is Efudex used for?

Efudex is used to treat a precancerous skin condition called actinic keratosis (sunspots) and a form of skin cancer called basal cell carcinoma.
How does Efudex work?

Efudex belongs to a group of drugs called antimetabolites. It works by targeting and killing the fast-growing cells found in actinic keratosis and basal cell carcinoma.
How long does it take for Efudex to work?

It may take two to four weeks to treat actinic keratosis and three to six weeks (but up to 12 weeks) to treat basal cell carcinoma.
What are the side effects of Efudex?

The most common side effects of Efudex include burning, crusting, rash, itching, scarring, soreness, and open sores.

How Can I Stay Healthy While Taking Efudex?

Efudex is one treatment option for actinic keratosis and certain forms of basal cell carcinoma. Early detection and treatment of these conditions can help prevent them from becoming serious. Refer below for some general tips to support your health:

Take medications as recommended by your healthcare provider.
Avoid exposure to UV rays (from the sun or indoor tanning beds) while taking Efudex and in the future.
Wear protective clothing, hats, sunglasses, and sunscreen.
Schedule annual skin exams with a dermatologist.
Perform monthly skin self-checks and let your healthcare provider know if you notice anything new, changing, or unusual.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

9 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

DailyMed. Efudex- fluorouracil cream.
Eisen DB, Asgari MM, Bennett DD, et al. Guidelines of care for the management of actinic keratosis: executive summary. J Am Acad Dermatol. 2021;85(4):945-955. doi:10.1016/j.jaad.2021.05.056
Jansen MHE, Kessels JPHM, Nelemans PJ, et al. Randomized trial of four treatment approaches for actinic keratosis. N Engl J Med. 2019;380(10):935-946. doi:10.1056/NEJMoa1811850
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Skin Cancer Foundation. Basal cell carcinoma overview.
Bargman H, Hochman J. Topical treatment of Bowen's disease with 5-Fluorouracil. J Cutan Med Surg. 2003;7(2):101-105. doi:10.1007/s10227-002-0158-6
Alnajjar HM, Lam W, Bolgeri M, Rees RW, Perry MJ, Watkin NA. Treatment of carcinoma in situ of the glans penis with topical chemotherapy agents. Eur Urol. 2012;62(5):923-928. doi:10.1016/j.eururo.2012.02.052
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By Christina Varvatsis, PharmD
Christina Varvatsis is a hospital pharmacist and freelance medical writer. She is passionate about helping individuals make informed healthcare choices by understanding the benefits and risks of their treatment options.

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