By-product of uric acid extracted from urea and considered an effective skin-soothing and skin-conditioning agent. Allantoin occurs naturally in the body. It can be extracted from plants (comfrey, chamomile) or made synthetically—the most common method for inclusion in cosmetics where it’s used in concentrations upwards of 2%.
Reference for this information:
Pharmacognosy Review, Volume 5, July-December 2011
International Journal of Toxicology, May 2010, Supplement, pages 84S-97S
Journal of Occupational Medicine and Toxicology, October 2008, ePublication