C 2624 (OTTO) Croton oil Cas no 8001-28-3 - used for croton oil today is as an active ingredient in phenol-based facial peels. Dermatologists, plastic surgeons and other practitioners can vary the amount of croton oil in the peel to customize the treatment for a particular patient or skin area, such as on the neck or around the eyes. In Malaysia, people use croton oil in lamps and in soap.