What is Efudex (fluorouracil)?

Efudex (fluorouracil) is a topical anti-metabolite medication that is used in the treatment of cancerous and precancerous skin growths, such as solar or actinic keratosis and superficial basal cell carcinoma. It does this by inhibiting the growth and further spread of abnormal skin cells that result in these conditions.

Efudex (Fluorouracil)
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What is Efudex (Fluorouracil)?

Efudex (fluorouracil) is a topical anti-metabolite medication that is used in the treatment of cancerous and precancerous skin growths, such as solar or actinic keratosis and superficial basal cell carcinoma. It does this by inhibiting the growth and further spread of abnormal skin cells that result in these conditions.

How is Efudex Used?

Efudex is used by applying a small amount of the topical medication to the affected area that requires treatment. This should be done once or twice per day after the area has been well cleaned. Most patients are required to use this medication daily for anywhere from two to six weeks for treatment, and the specifics of treatment will be determined by their prescribing physician based on the condition of their skin and the specific issue being treated.

Efudex should be applied to the patient’s skin with an applicator that does not contain metal, such as a cotton-tipped swab, or it may also be applied using a gloved hand. It is strongly advised that individuals coming into contact with this medication wear gloves and wash their hands well after use. If a patient chooses to apply Efudex without protection for their hands, they should wash their hands well immediately after application.

When using this topical medication for the treatment of solar or actinic keratosis, patients should apply Efudex twice per day, using an appropriate amount to fully cover the affected skin. They should continue using the medication until the lesions reach the erosion stage of the healing process and then cease use of the medication. While the treatment period for this condition typically ranges from two to four weeks, most patients do not experience complete healing of their keratosis lesions until 30 to 60 days after stopping treatment with Efudex.

When using Efudex for the treatment of superficial basal cell carcinomas, the medication should be applied daily in the same manner as how one would treat keratosis. It should be applied to the lesions with enough of the product being used to sufficiently cover the affected skin. The treatment period for superficial basal cell carcinoma lasts most commonly between three to six weeks. However, some patients may be required to use Efudex for 10 to 12 weeks before experiencing significant results and elimination of the carcinomas. When using this medication for the treatment of superficial basal cell carcinomas, patients should be monitored to ensure progress and appropriate treatment of the lesions.

This medication should not be applied immediately before sleep, and patients should use it at the same time each day.


Both the solution and cream forms of Efudex should be stored at an average room temperature of 77°F (25°C). If a patient must travel or otherwise be unable to maintain this temperature for their medication, Efudex may be allowed to reach a low temperature of 59°F (15°C) or a high temperature of 86°F (30°C).

Keep this medication out of the reach of children at all times.

Avoid skin contact with Efudex aside from the affected areas of skin being treated with the medication. If a patient or other individual has touched this medication, they should immediately wash it off with soap and water.

Efudex should never be allowed to come into contact with a person’s lips, nostrils, eyelids, or eyes.


Efudex is prescribed for the treatment of precancerous skin conditions, such as actinic keratosis (or solar keratosis), as well as cancerous skin growths such as superficial basal cell carcinoma. It blocks and limits further growth of the abnormal cells contributing to these skin conditions, preventing the worsening of their respective symptoms.

How Does Efudex Work?

Efudex functions by damaging the areas of skin that are being treated with the medication to promote healing and new growth, removing any evidence of actinic (or solar) keratosis or superficial basal cell carcinoma.

Being a chemotherapy medication, Efudex affects a patient’s RNA and DNA molecules, effectively inhibiting the growth and spreading of any cancerous cells. Additionally, abnormal cells are also more prone to absorbing Efudex, making this topical medication even more effective in resolving the conditions for which it is prescribed.

Within the first week of using Efudex, patients will begin to experience mild symptoms of inflammation where the medication was applied. After this initial inflammatory phase, additional redness and swelling will occur. Some patients begin to experience burning and crusting of the treated areas. The next phase of the treatment process sees the affected skin areas begin to exfoliate and remove themselves from the body, resulting in the removal of any lesions or tumors that may be present. After the damaged skin has been removed, new growth will occur, and the patient should experience a healing period of one to two weeks in which healthy skin regrows on the previously affected areas.


Efudex is available as both a solution and a cream.

The solution form of Efudex comes in either a 10 mL or a 25 mL drop dispenser container. It is available in the following strengths:

  • 2% fluorouracil (10 mL container)
  • 5% fluorouracil (10 mL container)
  • 5% fluorouracil (25 mL container)
  • 5% fluorouracil (25 mL container)

The cream form of Efudex is available in a 40 g tube with 5% fluorouracil.


There are no reported cases of an overdose occurring in patients taking Efudex.

If you have accidentally used too much of this medication and suspect that a significant amount of this medication may be present in your system, please call your doctor or local Poison Control Center for advice.

If you have gotten Efudex in your mouth, nose, or eyes, go to your nearest emergency room and seek out immediate medical attention.

Side Effects

Efudex has a unique healing process that may result in some common skin-related side effects as the medication works to eliminate the abnormal cells and produce healthy, non-cancerous cells to replace them. Dryness, tenderness, redness, or even a crusty texture on the skin is normal when using this medication as it begins to work and reduce the growth of the abnormal skin cells. Patients will have this damaged skin eventually shed off to reveal raw and fresh skin growth underneath. Upon reaching this point of healing in the treatment process, patients should contact their prescribing physicians regarding the continuation of the medication.

The most common side effects of taking Efudex are as follows:

  • darkening or scarring of the skin
  • redness and swelling of the skin
  • skin irritation (burning, itching, pain)

Some of these additional side effects may also occur. If you experience any of these while taking Efudex, you should stop taking the medication and discuss the symptoms with your doctor:

  • blistering
  • bloody diarrhea
  • chills
  • excessive swelling of the skin being treated
  • eye swelling or irritation
  • fever
  • severe abdominal pain
  • severe irritation, burning, or itching
  • significant pain
  • skin sores that are new
  • skin sores that become worse over time
  • symptoms of clotting problems
  • wheezing
  • weight loss
  • vomiting

Some users of Efudex have reported other symptoms as well. If you experience any of the following, please consult with your physician:

  • alopecia
  • conjunctivital issues
  • corneal problems
  • emotional distress
  • eosinophilia
  • irritability
  • medicinal taste in the mouth
  • nasal irritation
  • sleep difficulties
  • thrombocytopenia
  • unusual tear production (lacrimation)
  • watery eyes

Please contact your doctor if you experience any of the following symptoms of an allergic reaction while using this medication:

  • breathing difficulties
  • hives
  • swelling of the throat, tongue, lips, or face

Warnings & Precautions

When applying Efudex to the affected areas during treatment, some individuals have desired to cover the area with a dressing. Decreasing the airflow to the affected skin that is being treated has resulted in many users of this medication reporting worsened skin irritation. Please follow your doctor’s instructions regarding how to apply this medication and whether or not a dressing is suitable for your particular situation.


The safety and efficacy of using Efudex in patients below the age of 18 years old have not been determined.

Sensitivity to Sunlight

Patients using Efudex may experience increased sensitivity to sunlight during treatment. Those using this topical medication are advised to avoid excessive exposure to sunlight, the use of any sun lamps, and exposure to the cold or wind since all of these factors may further contribute to irritation of the skin. For individuals using Efudex for treatment that are unable to avoid being exposed to sunlight, they are advised to wear clothing with adequate protection from UV rays as well as use sunscreen with an SPF of at least 30. If swimming, sunscreen should be applied afterward to regain any potential loss of UV protection. If patients using Efudex manage to get sunburned, they should call their doctor regarding how to proceed with the treatment of the sunburn in addition to any potential changes that may need to be made to their ongoing treatment with Efudex.

DPD (Dihydropyrimidine Dehydrogenase) Deficiency

Patients with a deficiency of DPD should not be prescribed Efudex. This enzyme is responsible for breaking down Efudex within the body, and a deficiency of this enzyme will result in a buildup of Efudex within the patient’s system. Having an excess amount of this medication present within the body will cause patients to be far more likely to experience significant side effects.

Pregnancy and Breastfeeding

Efudex is not safe for use during pregnancy due to the risk of birth defects and harm to a patient’s unborn child. Patients using Efudex for treatment should take extra precautions to avoid becoming pregnant while being treated with this medication. If a patient is taking Efudex and becomes pregnant, they should contact their doctor immediately. It has been known to cause both ventricular septal defects in infants as well as miscarriage in pregnant individuals.

Patients currently or desiring to breastfeed are advised to avoid the use of Efudex while doing so since the associated risks of breastfeeding while taking this medication are unknown. It has not been determined whether Efudex may be passed through breastmilk, so patients who choose to do so are recommended to avoid using this topical medication.

Additional Medical Conditions

If you are currently undergoing radiation therapy, please speak to your doctor before beginning Efudex.

Additionally, report any allergies to preservatives, dyes, food, or medicines to your physician before beginning treatment with Efudex, as the ingredients propyl hydroxybenzoate and methyl hydroxybenzoate are known to cause allergic reactions in some individuals. The propylene glycol and stearyl alcohol may also result in an increased risk of skin irritation in some patients as well.

Drug Interactions

Speak to your doctor about any medications or herbal supplements you are currently taking before beginning treatment with Efudex. Discuss any concerns you may have with your doctor or a trusted pharmacist.

Drugs That Are Known to Interact with Efudex

These medications are known to interact with Efudex and may increase your chances of experiencing adverse Efudex side effects:

  • capecitabine (Xeloda)

Alternative Medications

For patients who are unable to take Efudex or experiencing significant adverse side effects, alternative medications and treatment methods may be used to treat some of the associated conditions for which this medication is commonly prescribed.

For the treatment of basal cell carcinoma:

  • Aldara (imiquimod)
  • cryosurgery
  • PDT (photodynamic therapy)

For the treatment of solar or actinic keratosis:

  • Carac (fluorouracil)
  • Fluoroplex (fluorouracil)
  • Klisyri (tirbanibulin)
  • Solaraze (diclofenac)
  • Tolak (fluorouracil)
  • Zyclara (imiquimod)

Frequently Asked Questions

Efudex should not be used by pregnant individuals due to the risk of harm to the patient’s unborn child as well as the risk of causing birth defects. Individuals using Efudex for treatment should exercise extra caution to avoid pregnancy from occurring while using Efudex. If you are currently being treated with Efudex and become pregnant, please contact your doctor immediately.

The active ingredient in both the solution and the cream forms of Efudex is fluorouracil. The inactive ingredients in the solution are as follows: disodium edetate, parabens (propyl and methyl), hydroxypropyl cellulose, tris (hydroxymethyl) aminomethane, and propylene glycol. The inactive ingredients in the cream form of Efudex include the following: purified water, parabens (propyl and methyl), polysorbate 60, propylene glycol, stearyl alcohol, and white petrolatum.

Compared to surgery, Efudex is far less likely to cause skin discoloration or scarring when used for treatment.

Using a moisturizer that is petroleum-based, such as Vaseline or Aquaphor, may be safe to use for the reduction of side effects associated with treatment. However, all patients should clear the use of such products with their prescribing physician to ensure the continued efficacy of Efudex on the affected skin areas.

For many patients, the treatment process may become quite uncomfortable. However, the damage inflicted upon the skin is a positive sign as it means the medication is working. Over time, the discomfort and unpleasant appearance of the treated skin will fade and be replaced by healthy, fresh skin.

Cosmetic products should not be applied to the skin being treated unless a patient has been instructed to do so by their doctor.

In a 2012 study involving fluorouracil (the active ingredient in Efudex), the results of the studied indicated that this medication may impact a patient’s immune system.

The patient’s doctor should provide them with advice and guidelines regarding when to stop using Efudex, but most patients are able to stop applying the medication within three to four weeks once the skin has reached the ulceration phase of the treatment process.

Most patients that have used Efudex for treatment have reported smoother and softer skin with fewer wrinkles.

Patients should not stop using Efudex without first consulting their prescribing physician. Although certain phases of the treatment may look very unappealing and be uncomfortable, each stage is essential in the treatment process and should not be stopped or changed without seeking medical advice beforehand.

Efudex may take up to two hours before it is completely absorbed into the patient’s skin. This longer time frame is why patients are advised to avoid applying the topical medication before bedtime.

When using Efudex, patients should not wash the areas being treated with this medication for at least three hours after the topical solution or cream has been applied.

Some patients taking Efudex have experienced insomnia or difficulty sleeping.

Unfortunately, due to its mechanism of action, Efudex may become quite painful for some patients using the medication, especially depending upon the location of the area of skin being treated. If you are using Efudex and struggling with the pain being caused by the treatment, please speak to your prescribing physician about appropriate medications or other methods that are safe to use alongside Efudex to manage unpleasant symptoms and discomfort.

Efudex is primarily absorbed by abnormal cells, so it should not impact the health and appearance of a patient’s healthy skin that may be near the lesions being treated with this medication.

After a patient has completed their final application of Efudex on the affected skin, they may encourage speedy healing and good skin health by applying Aquaphor Healing Ointment or Vaseline to the areas most impacted by treatment. Do not use any other medication, ointments, or lotions without first consulting your physician.

During treatment, patients are far more susceptible to sun-related damage. However, even after treatment has ceased, a patient’s skin is likely to remain pink and sensitive for additional months, so precautions should be taken to accommodate the continued risk of sunburn and other sun-related concerns.