First, make sure it's aloe vera. Second, check that you're not
allergic to it; put a little on the inside of your elbow then cover
for 24hrs and see if you get a rash. Here's a couple of great sites:

http://www.wholehealthmd.com/refshel...,10001,00.html
http://www.botanical.com/botanical/mgmh/a/aloes027.html