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What is fluorouracil?

Fluorouracil (also called 5-FU or Adrucil®) is an anticancer medicine. It is a clear to yellow-colored liquid given by vein (IV).

Fluorouracil can pose a health hazard to caregivers. All caregivers should take safety precautions while giving this drug. For 48 hours after this drug is given, the patient’s body fluids can contain the drug. During that 48-hour period, caregivers should follow safety guidelines when handling the patient’s vomit, blood, urine, and bowel movements, including diapers. These guidelines include wearing gloves when cleaning up body fluids. For a complete list of safety precautions, see “Do you know… Protecting caregivers from drug hazards.”

Laboratory testing for fluorouracil

An enzyme in the body called dihydropyrimidine dehydrogenase (DPYD) has the ability to break down certain medicines including fluorouracil. A genetic test can be done to determine how well your DPYD breaks down medicines. If your body breaks down this medicine more slowly, you should receive lower doses or avoid fluorouracil. For more information about DPYD and its effect on fluorouracil, talk with your doctor or pharmacist, and see “Do you know… DPYD and Medicines.” For more details, go to

Possible side effects of fluorouracil


  • Nausea and vomiting
  • Bruising at site of injection
  • Allergic reaction – rash, itching, tightness in the chest, trouble breathing, or swelling of the mouth, face, lips, tongue, or throat.

Later (usually more than a day after treatment starts)

  • Low blood counts with a higher risk of infection, bleeding, anemia, and tired feeling
  • Mouth sores
  • Sores on the hands and feet
  • Stomach ulcers and bleeding
  • Diarrhea
  • Skin rash and more sensitive to the sun and sun lamps
  • Change in the color of the skin and nails
  • Hair loss
  • Headache
  • Feeling confused

These are the most common side effects, but there may be others. Please report all side effects to the doctor or nurse.

In case of a severe side effect or reaction, call the doctor, nurse, or pharmacist at 901-595-3300. If you are outside the Memphis area, dial toll-free 1-866-2STJUDE (1-866-278-5833), and press 0 once the call is connected.

Pregnancy risk with fluorouracil

This medicine can be harmful to an unborn child. Avoid becoming pregnant during treatment. Contact one of your caregivers at St. Jude if you are sexually active or think you may be pregnant.

Special instructions for fluorouracil

  • If you have nausea or vomiting, tell your doctor. The doctor can order medicine to keep you from feeling sick and throwing up while you are being treated with fluorouracil.
  • This medicine can make you sensitive to the sun. Use a sunscreen lotion and wear clothing to protect your skin from the sun while you are receiving fluorouracil.
  • The staff will take blood samples to check blood counts and to check liver and kidney function while you are treated with fluorouracil.
  • If you have severe diarrhea, severe vomiting, sore throat, or stomach pain, tell your doctor right away.
  • Fluorouracil is usually given with another medicine called leucovorin. Leucovorin will help to increase the effect of fluorouracil in treating your cancer.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

ATENCIÓN: si habla español, tiene a su disposición servicios gratuitos de asistencia lingüística. Llame al 1-866-278-5833 (TTY: 1-901-595-1040).

تنبيه: إذا كنت تتحدث باللغة العربية فيمكنك الاستعانة بخدمات المساعدة اللغوية المتوفرة لك مجانا. .يرجى الاتصال بالرقم. 5833-278-866-1  (الهاتف النصي: 1040-595-901-1).