I am on my third week using Carac 5% fluorouracil once per day for 4-6 wks for actininc keratosis on my face. All areas were previously determined to be pre-cancerous. It is amazing how selectively the cream has attacked the sun damaged spots on my cheeks, right above my upper lip and on my nose. The damaged parts are bright red, dry, sore and scabbed over while adjacent skin is perfectly normal. Unbelieveable scientific breakthrough to search out and destroy potential skin cancers! I look awful and am a bit scared by what is happening to my nose (looks like the skin being attacked is pretty deep) but still in awe of the discovery/treatment and hoping for a cure/cancer preventative despite all the sun damage. Some side effects that I did not expect are: diarrhea, a bit of stomach upset and insomnia. Have not had the cold sore looking spots develop yet but I have had that look in the past while having actinic keratosis treated with liquid nitrogen and it is awful. Makes you want to hide, for sure. My heart goes out to all of you who are having that particular side effect. Makes me count my blessings that I only have a nose that looks like a crow has pecked at it for several days! Hang in there, everyone. I hear that the results are usually spectacular...easier than skin cancer surgery and far more effective. Will let you know how I feel in 2-3 weeks when my nose will probably be non-existent. Regards, barngirl (too much time outside with the equines and not protected from the sun)