Spanky....your statement "Remember Carac is not as strong as the Efudex 5%. is not really accurate. Again, Carac and Efudex are just the BRAND NAMES, of fluorouracil. I used the generic and it was simply flourouracil 5%. Yes, you can get different percentages/stregth and apply 1 or 2 times a day, etc. But same drug. Here is another simple description at this link:
http://www.drugs.com/mtm/carac.html
And no, not all cells die off, the point is the flourouracil targets the "bad" cells. Just read up on floourouracil. Google it.
Whitey
And here is a good description on Wikipedia:
http://en.wikipedia.org/wiki/Fluorouracil