Fluorouracil (5-FU) is a chemotherapy compound which has been around for a long time. For topical (on the skin) use, it is sold as Efudex and Carac, and is used to kill cancerous or pre-cancerous skin lesions. Actinic Keratosis, or Solar Keratosis, is a condition in which there are generally many spots, some visible and some not, some of which will become skin cancer if untreated. So, fluorouracil is often prescribed as a method of killing many of the pre-cancerous spots before they become cancer and have to be removed by freezing or cutting.
The Efudex treatment (or Carac treatment) is itself not very pleasant. The drug is prescribed when it is deemed to be preferable to addressing the individual Basal Cell or Squamous Cell carcinomas one at at time over a period of years.
Efudex is normally prescribed to be applied twice a day for two to four weeks. The side effects of Efudex are described and photographically documented elsewhere on this site. To be more accurate, though, what we think of as side effects are really the primary effect of the chemotherapy agent, fluorouracil, attacking cancerous cells. So when the “side effects” are “bad” (meaning uncomfortable, painful, unsightly) that is what one’s dermatologist would call a “good” reaction…the treatment was needed and is being effective.
