keratosis
"Have used it for pre-cancer on my face probably 6 times since 1996. 

Using it now on a couple of spots on the back of my hand. 

Have always found it perfectly effective. Yes, after a couple weeks it begins to look raw and ugly, but that quickly clears up after treatment stops. In every case the spots were cured. Luckily I have never experienced any of the pain or itchiness that others have reported. Perhaps mostly the ones who had problems bothered to report?

And I still have the original tube of the produce I got back in 1996, and yes, it still works. There was enough in it to keep me going when needed it and obviously it didn't go bad. The fact it's in a metal tube may have enabled it's long life vs a plastic tube."