5-Fluorouracil (5-FU) is a medication applied to the skin for the treatment of actinic keratoses (AKs) and some types of non-melanoma skin cancer that are limited to the top layer of skin (SCC in situ).
5-FU is a topical chemotherapy that kills sun damaged skin cells. It can also damage normal skin cells and result in significant skin irritation.
Using 5-FU usually results in a mild to severe burning sensation. After 5-10 days of treatment, the sun-damaged parts of treated skin become red and irritated. Sores and crusts may appear with ongoing use. These raw areas result from the destruction of defective skin cells and are an expected side effect of 5-FU treatment.
5-FU is to be used as directed, usually for two to eight weeks. It is applied once or twice a day after washing the area that is to be treated with plain water. A very small amount of 5-FU should be gently rubbed into all of the treatment areas with a fingertip. It is important to apply it the whole area to be treated, not just lesion that is visible to the naked eye.
After applying 5-FU to the skin, rinse your hands thoroughly with water (or use a glove to apply the medication).
Some people who experience significant irritation may be instructed to apply 5-FU in cycles. This involves using the medication for a specific period of time, stopping the medication for a period and then resuming treatment again for a specific period of time.
Your doctor will determine if cycle therapy is appropriate for you and the duration of the "treatment" and "rest" periods.
Take 5-FU exactly as directed by your doctor.
Read the medication guide that you receive with the medication for a complete list of possible side effects.
Speak with your doctor if you are concerned about possible side effects that you may be experiencing.