5-Fluorouracil (Generic Name)

Other Names: 5-FU, Adrucil®, Efudex®

About This Drug

5-fluorouracil is used to treat cancer. This drug is given in the vein (IV), by mouth, or on the skin.

Possible Side Effects (More Common)

  • Bone marrow depression. This is a decrease in the number of white blood cells, red blood cells, and platelets. This may raise your risk of infection, make you tired and weak (fatigue), and raise your risk of bleeding.
  • Soreness of the mouth and throat. You may have red areas, white patches, or sores that hurt.
  • Loose bowel movements (diarrhea) that may last for a few  days
  • Nausea and throwing up (vomiting). These symptoms may happen within a few hours after your treatment and may last up to 24 hours. Medicines are available to stop or lessen these side effects.
  • Hair loss or thinning. Hair loss is often complete scalp hair loss and can involve loss of eyebrows, eyelashes, and pubic hair.  You may notice this a few days or weeks after treatment has started.  Most often hair loss is temporary; your hair should grow back when treatment is done.
  • Veins that are used to get 5-Flourouracil by IV may get darker.
  • Nails and skin may get darker. This is often temporary and will fade when the drug treatment is done.
  • Hand-and-foot syndrome.  The palms of your hands or soles of your feet may tingle, become numb, painful, swollen, or red. 
  • Sensitivity to light (photosensitivity). Photosensitivity means that you may become more sensitive to the light from the sun, sun lamps, and tanning beds. Your eyes may water more, mostly in bright light.
  • Decreased appetite (decreased hunger)

Possible Side Effects (Less Common)

  • Raised, red rash on your arms, legs, back, or chest
  • Darkening or partial loss of fingernail and toenail beds
  • Dry, itchy, or red eyes
  • Changes in lung tissue may happen with large amounts of this drug. These changes may not last forever, and your lung tissue may go back to normal. Sometimes these changes may not be seen for many years. You may get a cough or have trouble catching your breath.
  • Effects on the heart: This drug can weaken the heart and lower heart function. Your heart function will be checked as needed. You may have trouble catching your breath, mainly during activities. You may also have trouble breathing while lying down, and have swelling in your ankles

Treating Side Effects

  • Drink 6-8 cups of fluids every day unless your doctor has told you to limit your fluid intake due to some other health problem. A cup is 8 ounces of fluid. If you throw up or have loose bowel movements, you should drink more fluids so that you do not become dehydrated (lack water in the body from losing too much fluid).
  • Mouth care is very important. Your mouth care should consist of routine, gentle cleaning of your teeth or dentures and rinsing your mouth with a mixture of 1/2 teaspoon of salt in 8 ounces of water or 1/2 teaspoon of baking soda in 8 ounces of water. This should be done at least after every meal and at bedtime.
  • If you have mouth sores, avoid mouthwash that contains alcohol. Also avoid alcohol and smoking because they can bother your mouth and throat.
  • If you get a rash, do not put anything on it unless your doctor or nurse says you may. Keep the area around the rash clean and dry. Ask your doctor for medicine if your rash bothers you.
  • Talk with your nurse about getting a wig before you lose your hair.  Also, call the American Cancer Society at 800-ACS-2345 to find out information about the “Look Good, Feel Better” program close to where you live. It is a free program where women getting chemotherapy can learn about wigs, turbans and scarves as well as makeup techniques and skin and nail care.
  • Ask your doctor or nurse about medicine that is available to help stop or lessen the loose bowel movements.
  • Wear dark sunglasses and use sunscreen with SPF 30 or higher when you are outdoors even for a short time.
  • Cover up when you are out in the sun. Wear wide-brimmed hats, long-sleeved shirts, and pants. Keep your neck, chest, and back covered.

Food and Drug Interactions

There are no known interactions of 5-fluorouracil with food. This drug may interact with other medicines. Tell your doctor and pharmacist about all the medicines and dietary supplements (vitamins, minerals, herbs and others) that you are taking at this time. The safety and use of dietary supplements and alternative diets are often not known. Using these might affect your cancer or interfere with your treatment. Until more is known, you should not use dietary supplements or alternative diets without your cancer doctor's help.

When to Call the Doctor

Call your doctor or nurse right away if you have any of these symptoms:

  • Fever of 100.5 F (38 C) or higher
  • Chills
  • Wheezing or trouble breathing
  • Feeling that your heart is beating in a fast or not normal way (palpitations)
  • Easy bleeding or bruising 
  • Blurred vision or other changes in eyesight
  • Loose bowel movements (diarrhea) 4 times in one day, or diarrhea with lack of strength or a feeling dizzy or lightheaded.
  • Nausea that stops you from eating or drinking
  • Throwing up more than 3 times in a day

Call your doctor or nurse as soon as possible if you have any of these symptoms:

  • Trouble walking or changes in the way you walk, feeling clumsy when buttoning clothes, opening jars, or other routine hand motions
  • Headache that does not go away
  • Pain in your mouth or throat that makes it hard to eat or drink
  • Painful, red, or swollen areas on your hands or feet.

Sexual Problems and Reproduction Concerns

  • Sexual problems and reproduction concerns may happen. In both men and women, this drug may affect your ability to have children. This cannot be determined before your treatment. Talk with your doctor or nurse if you plan to have children.  Ask for information on sperm or egg banking.
    • In men, this drug may interfere with your ability to make sperm, but it should not change your ability to have sexual relations.
    • In women, menstrual bleeding may become irregular or stop while you are getting this drug. Do not assume that you cannot become pregnant if you do not have a menstrual period.
    • Women may go through signs of menopause (change of life) like vaginal dryness or itching. Vaginal lubricants can be used to lessen vaginal dryness, itching, and pain during sexual relations.
    • Genetic counseling is available for you to talk about the effects of this drug therapy on future pregnancies. Also, a genetic counselor can look at the possible risk of problems in the unborn baby due to this medicine if an exposure happens during pregnancy.
  • Pregnancy warning: This drug may have harmful effects on the unborn child, so effective methods of birth control should be used during your cancer treatment.
  • Breast feeding warning: Women should not breast feed during treatment because this drug could enter the breast milk and badly harm a breast feeding baby.

Revised August 2014

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