Fluorouracil is used to treat breast cancer, head and neck cancer, gastric cancer, colorectal cancer and pancreatic cancer. Learn how the medication is given, its common side effects, special precautions to watch out for, and more.

What is this medication for?

Fluorouracil is a chemotherapy medication used to treat certain cancers such as breast cancer, head and neck cancer, gastric cancer, colorectal cancer and pancreatic cancer. It may be used on its own or in combination with other chemotherapy drugs. It works by blocking the cell division process, causing the cancer cells to eventually die.

How should I take or use this medication?

Fluorouracil is injected into the vein (given intravenously). It can be given as an injection (over a few minutes) or as an infusion (a drip). It may also be given as a continuous infusion through a pump device.

What precautions should I take when taking or using this medication?

Inform your healthcare professional if: 

• You are allergic to this medication or another chemotherapy medication called capecitabine, or any of the other ingredients of this medication.
• You are pregnant, planning to become pregnant, or breastfeeding 
  • For female patients who could become pregnant: You should use effective birth control during treatment and for 6 months after your last treatment.
  • For male patients with female partners who could become pregnant: You should use effective birth control during treatment and for 3 months after your last treatment.
  • Do not breastfeed during treatment.
• You are taking any other medications, including supplements, traditional medications and herbal remedies. 

What are some common side effects of this medication?

• Decreased white blood cells, red blood cells and platelets. This may put you at increased risk of infections, bleeding or bruising, and feeling tired. 
  • To reduce your risk of infection:
    • Practice good personal hygiene.
    • Avoid eating raw or half-cooked food.
    • Avoid crowded places and coming into close contact with people who are not feeling well. Wear a face mask when you’re going out.
  • To reduce your risk of bleeding:
    • Be careful when using sharp objects such as knives.
    • Brush your teeth with a soft-bristled toothbrush.
• Diarrhea
  • Drink more water or clear fluids to replace the fluids lost.
  • Avoid oily, spicy food or dairy products.
• Mild nausea or vomiting
  • Take small frequent meals. 
  • Avoid food/smells that may make you feel nauseous such as oily, fried food or strong-smelling food.
• Mouth ulcers
  • Avoid eating hard or spicy foods.
  • Brush teeth with a soft-bristled toothbrush after eating and at bedtime.
  • Use a non-alcohol-containing mouthwash to maintain mouth hygiene after meals.
• Nail changes. Nails may become more brittle, or have lines on the nail surface.
  • Keep nails short and avoid constant contact with water and harsh detergents.
• Skin changes, such as darkening of the skin and dry skin. 
  • Protect yourself from the sun by using sunscreen, wearing long-sleeved clothes and long pants, and avoid spending time directly under the sun.
  • Use moisturizer regularly to prevent dry skin, especially to your hands and feet.
• Hand-foot syndrome (for patients receiving fluorouracil by continuous infusion) - whereby palms of the hands or soles of the feet may become red, numb, sore or have skin peeling.
  • Avoid activities which cause excessive rubbing on your hands and feet, e.g. chopping food with a knife. 
  • Wear comfortable and supportive footwear.
  • Avoid constant soaking in hot water  

What are some rare but serious side-effects that I need to seek medical advice immediately?

• Symptoms of infection such as high fever of 38 ⁰C and above
• Unusual bleeding, bruising or black sticky stools
• Severe diarrhea (more than 4 times a day)
• Symptoms of heart problems, such as chest pain, irregular heartbeat, feeling breathless with swelling of the lower legs
• Symptoms of problems with the nervous system, such as confusion, problems with movement coordination, or unusual eye movements
• Severe hand-foot syndrome such as swelling, pain, bleeding or blisters on the skin over the palms of the hands or the soles of the feet (for patients receiving continuous infusion)
• Drug allergy. The symptoms of a drug allergy include one or more of the following: 
  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should see your healthcare professional immediately.

What food or medication should I avoid when I take or use this medication?

Avoid taking traditional Chinese medications (TCM) or “jamu” when you are on this medication.

What else should I know about this medication?

This medication is also known as “5-Fluorouracil” or “5-FU”.

Disclaimer

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Feb 2024