Not to worry...I completed six weeks of Carac treatment last year and experienced none of the nasty side effects you mentioned. I had had several Mohs procedures along with some "burn offs," mostly on my face but also on my legs. Like many 60+ years olds, I had gone blythly through childhood enduring excessive amounts of unprotected exposure from the sun.
After seeing a picture of me with my daughter at her wedding I was appalled at how evident were all the redish lesions on my face- mostly my forehead. When the dermatologist at my last procedure suggested Carac I jumped at it. After a few days I looked worst than ever as the fluorouracil
attacked the facial lesions turning them a bright red. But eight weeks after starting treatment I was practically lesion free. My lone complaint is that Carac is pricey and the tubes of cream are pretty stingy. Also, your doctor will prescribe another less expensive cream that moderates the cosmetic appearance of the cream. My family says I'm looking a lot better. So, go for it!