Sensitizers - You know how sometimes you can use a product for a while and then all of a sudden you break out and can't figure out why? That's a sensitizer. You are okay at first but after a while you a become very allergic to it.

Diazolidinyl Urea is a sensitizer it is used as an emulsifier (helps keep product from separating).

Stearic Acid - may be a sensitizer, may be made from animal or vegetable fats (know your source, some are made naturally) used to give pearliness to creams.