Side Effects

Drug information provided by: IBM Micromedex

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.

Also, because of the way these medicines act on the body, there is a chance that they might cause other unwanted effects that may not occur until months or years after the medicine is used. These delayed effects may include certain types of cancer, such as leukemia. Discuss these possible effects with your doctor.

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

More common

  1. Diarrhea
  2. heartburn
  3. sores in mouth and on lips

Less common

  1. Black, tarry stools
  2. cough or hoarseness, accompanied by fever or chills
  3. fever or chills
  4. lower back or side pain, accompanied by fever or chills
  5. nausea and vomiting (severe)
  6. painful or difficult urination, accompanied by fever or chills
  7. stomach cramps


  1. Blood in urine or stools
  2. pinpoint red spots on skin
  3. unusual bleeding or bruising

Check with your doctor as soon as possible if any of the following side effects occur:


  1. Chest pain
  2. cough
  3. shortness of breath
  4. tingling of hands and feet, followed by pain, redness, and swelling
  5. trouble with balance

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:

More common

  1. Loss of appetite
  2. nausea and vomiting
  3. skin rash and itching
  4. weakness

Less common

  1. Dry or cracked skin

This medicine often causes a temporary loss of hair. After treatment with fluorouracil has ended, normal hair growth should return.

After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:

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.