Interesting that you bring this up.I have roseaca and lots of skin allergies--can't use most sun screens, for example. For the most part, I don't use salon or drugstore products. Did a quick ingredient search and two of the products that make my scalp burn (CK and Bioterra Curl Creme) both have Propylene Glycol. Couldn't quickly find ingredients for two of the others--Bioterra Gel and Shea M LI. When I looked at other brands that I use without problem (in CurlMart), no Propylene Glycol. I'll have to look at some of my other products when I go upstairs.