answered Nov 22, 2009 at 03:58PM
I've never had a problem with it in medications, but I have a problem with it in shampoos. It causes me to get red, itchy bumps all over my scalp and hairline. If the shampoo is really bad I'll also get the itchy rash on my neck and behind my ears. I've had this problem most of my life, but it took a long time for me to figure out what it was.
It's hard to find shampoos without this ingredient, but some shampoos have less of the ingredient than others. I've been taking Xyzal for a while and I don't seem to have nearly as bad of a reaction anymore.
I know this doesn't answer your question, but they also says it's safe for shampoos, but I'm skeptical. There seem to be a lot of people who have allergic reactions or irritation from it.