Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Fluorouracil.

Blood clotting: Fluorouracil can reduce the number of platelet cells in the blood and increase your risk of bleeding. Platelets help the blood to clot, and a shortage could make you bleed more easily.

Tell your doctor immediately if you notice any signs that your blood is not clotting as quickly as usual (e.g., black and tarry stools, blood in the urine, easy bruising, or cuts that won't stop bleeding). Your doctor will do blood tests regularly to monitor the number of platelets in your blood.

Cardiovascular effects: Fluorouracil has been reported to cause effects on the heart and circulatory (blood vessels) system. Reports of Heart Attack, Angina, irregular heart rhythm, and heart failure have been reported with the use of fluorouracil.

If you have heart disease or any other diseases of the heart and blood system, discuss with your doctor how Fluorouracil may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Fluorouracil, and whether any special monitoring is needed.

Infection: In addition to killing cancer cells, Fluorouracil can reduce the number of cells that fight infection in the body (white blood cells). If possible, avoid contact with people with contagious infections.

Tell your doctor immediately if you notice signs of an infection such as fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness. Your doctor will do blood tests regularly to monitor the number of specific types of blood cells in your blood.

Kidney function: Reduced kidney function can affect the dose of fluorouracil that a person needs. If you have Kidney Disease or reduced kidney function, discuss with your doctor how Fluorouracil may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Fluorouracil, and whether any special monitoring is needed.

Liver function: The liver helps remove fluorouracil from the body. When the liver is not working well, the risk of side effects is increased. If you have reduced liver function or liver disease, discuss with your doctor how Fluorouracil may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Fluorouracil, and whether any special monitoring is needed.

Red blood cells: Fluorouracil may cause low levels of red blood cells. If you experience symptoms of reduced red blood cell count (anemia) such as shortness of breath, feeling unusually tired, or pale skin, contact your doctor as soon as possible.

Serious medical conditions, treatments, or surgery: People who have had recent major surgery, treatment with other anticancer medications that suppress bone marrow function, cancers that have spread to the bone, or high-dose radiation to the spine, ribs, or pelvis may experience more severe side effects of fluorouracil.

If you have experienced any of the above, or any other serious medical condition, discuss with your doctor how Fluorouracil may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Fluorouracil, and whether any special monitoring is needed.

Skin sensitivity: Fluorouracil can make the skin more sensitive to sun exposure. An exaggerated Sunburn reaction may occur. Avoid exposure to excessive sunlight, including sunlamps and tanning beds, and use sunblock with minimum SPF 30.

Vaccines: Before starting Fluorouracil, all your immunizations should be up to date. Live vaccines (e.g., BCG, yellow fever) are not recommended for people taking Fluorouracil. Talk to your doctor if you need any vaccinations while taking Fluorouracil.

Pregnancy: There is a possibility of birth defects if fluorouracil is being used at the time of conception, or if it is taken during pregnancy. Use effective birth control while you are being treated with Fluorouracil. If you become pregnant while taking Fluorouracil, contact your doctor immediately.

Breast-feeding: It is not known if fluorouracil passes into breast milk. Due to the potential for serious harm to the baby, women receiving fluorouracil should not breast-feed.