Common side effects of 5FU include nausea, weakness, loss of appetite and a skin rash or itching, according to Drugs.com. The side effects of 5FU, which is also known as fluorouracil, depend on the way the drug is administered.
Doctors often prescribe 5FU to treat the symptoms of breast, colorectal, pancreatic or stomach cancer, according to Drugs.com. In this case, doctors inject a solution of the drug into the patient's veins. Common side effects include diarrhea, heartburn and sores on the mouth and the lips. Patients should seek medical attention for these side effects. It is also common for patients to experience nausea, vomiting, loss of appetite and weakness.
A cream that contains 5FU is useful for treating certain types of skin cancer, as reported by WebMD. This cream often causes redness and dryness of the skin, as well as burning, pain, swelling and loss of the upper layer of skin. Patients should seek medical attention if they experience more serious side effects of 5FU cream, including hives, bloody diarrhea, fever, chills or vomiting. Belly pain is another side effect that requires medical attention.
Some patients find that their side effects go away after they have been taking 5FU for a while, according to WebMD. Patients who continue to experience side effects should consult their doctor, who might be abe to lower the dose or suggest an alternative.