I've been using Efudix on a few small patches of Actinic Keratosis on my scalp. It says do a thin layer but also don't use too much. I'm getting a few prickles after 6 days use but I expected the skin to become a lot more sore. I'm only rubbing in a very small amount so it disappears and the cream isn't visible on the skin. I wonder if I'm putting on enough.