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Fluorouracil (Topical)

Medically reviewed by Last updated on Apr 24, 2022.

Commonly used brand name(s)

In the U.S.

  • Carac
  • Efudex
  • Fluoroplex

Available Dosage Forms:

  • Cream
  • Solution

Therapeutic Class: Antineoplastic Agent

Pharmacologic Class: Antimetabolite

Uses for fluorouracil

Fluorouracil topical is used to treat actinic or solar keratoses and a type of skin cancer called superficial basal cell carcinoma.

Fluorouracil is available only with your doctor's prescription.

Before using fluorouracil

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For fluorouracil, the following should be considered:


Tell your doctor if you have ever had any unusual or allergic reaction to fluorouracil or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.


Appropriate studies have not been performed on the relationship of age to the effects of fluorouracil topical in the pediatric population. Safety and efficacy have not been established.


No information is available on the relationship of age to the effects of fluorouracil topical in geriatric patients.


There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking fluorouracil, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using fluorouracil with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Brivudine
  • Measles Virus Vaccine, Live
  • Mumps Virus Vaccine, Live
  • Rotavirus Vaccine, Live
  • Rubella Virus Vaccine, Live
  • Tegafur
  • Varicella Virus Vaccine, Live
  • Zoster Vaccine, Live

Using fluorouracil with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Acenocoumarol
  • Adenovirus Vaccine
  • Allopurinol
  • Azanidazole
  • Bacillus of Calmette and Guerin Vaccine, Live
  • Benznidazole
  • Cholera Vaccine, Live
  • Cimetidine
  • Dengue Tetravalent Vaccine, Live
  • Influenza Virus Vaccine, Live
  • Isoconazole
  • Levoleucovorin
  • Methotrexate
  • Metronidazole
  • Nimorazole
  • Ornidazole
  • Oxypurinol
  • Phenprocoumon
  • Poliovirus Vaccine, Live
  • Secnidazole
  • Smallpox Vaccine
  • Tamoxifen
  • Tinidazole
  • Typhoid Vaccine, Live
  • Warfarin
  • Yellow Fever Vaccine

Using fluorouracil with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

  • Fosphenytoin
  • Leucovorin
  • Levamisole
  • Phenytoin
  • Thiamine

Interactions with food/tobacco/alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other medical problems

The presence of other medical problems may affect the use of fluorouracil. Make sure you tell your doctor if you have any other medical problems, especially:

  • Dihydropyrimidine dehydrogenase (DPD) enzyme deficiency—Should not be used in patients with this condition.

Proper use of fluorouracil

It is very important that you use fluorouracil only as directed by your doctor. Do not use more of it, do not use it more often, and do not use it for a longer time than your doctor ordered. To do so may cause your skin to become irritated.

Fluorouracil is for use on the skin only. Do not get any of fluorouracil near or around your eyes, nose, or mouth. If it does get on these areas, rinse it off with water and check with your doctor right away.

To use the cream or solution:

  • Wash your hands with soap and water before and after using fluorouracil.
  • Apply enough amount of the medicine to each affected area.
  • You may use a glove, nonmetal applicator, or fingers to apply fluorouracil.
  • Do not bandage or otherwise wrap the skin being treated unless directed to do so by your doctor.


The dose of fluorouracil 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 fluorouracil. 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.

Missed dose

If you miss a dose of fluorouracil, apply it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule.


Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

Keep fluorouracil away from pets. Do not allow pets to contact the skin where the medicine is applied. Throw away or clean any cloth or applicator that may still have some of fluorouracil. Do not leave any medicine on your hands, clothing, carpet, or furniture.

Precautions while using fluorouracil

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

Using fluorouracil 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.

Fluorouracil 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.

Fluorouracil 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.

Fluorouracil side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Incidence not known

  • Black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • chest pain
  • chills
  • cough
  • fever
  • painful or difficult urination
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips
  • swollen glands
  • trouble breathing
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Incidence not known

  • Dry, rough, or scaly skin
  • loss or thinning of the hair
  • raised, dark red, wart-like spots on the skin, especially when used on the face
  • swelling or inflammation of the mouth
  • tearing of the eyes
  • trouble sleeping

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.