Fluorouracil (5-FU) is a type of chemotherapy that exerts its anti-cancer effect by preventing the production of DNA in the cell. Lack of functional DNA prevents the cancer cell from reproducing and making vital proteins, which then results in death of the cell.
Topical fluorouracil is used to treat actinic keratosis and superficial basal and squamous cell skin cancers. The medication destroys sun damaged skin cells, but can also damage normal skin it comes into contact with or cause skin irritation.
Topical fluorouracil (5-FU) comes as a topical cream, available in 2 strengths (5-FU also comes in an IV solution, to be given into a vein). Your healthcare provider will determine which strength is right for your condition and tell you how often to use the cream (typically 1-2 times a day). Most patients will use the cream for 2-12 weeks, depending on the condition being treated and the response to treatment.
To apply the cream:
The treatment area will typically have a burning sensation and, after several days of treatment, become red and crusted. The area will look worse than before treatment, which will likely continue for a few weeks after treatment stops.
Avoid sun exposure during and after treatment with topical 5-FU, as this can make the skin reaction worse.
You may experience any of the following in the treated area: darkening of skin color, pain, irritation, redness, itching, scarring, rash and skin ulcerations.
Drug absorption is limited with topical use, but some patients have a deficiency of the enzyme (DPD) needed to break down 5-FU. These patients can develop serious toxicity. If you experience diarrhea or sores in your mouth, report this to your healthcare provider right away.
Women should not become pregnant while using this medication or use this medication while pregnant as it can cause harm to the fetus. Talk with your healthcare provider right away if you think you may be pregnant.