Chlorphenesin

Chlorphenesin is a preservative and antifungal used in creams, lotions, and makeup at up to 0.3 percent, often alongside phenoxyethanol. For adult skin the record is reassuring: the CIR panel reviewed it and found it safe at use levels, a non-irritant in patch testing, and an uncommon cause of allergy, with only a handful of contact-dermatitis cases on record across the more than 1,300 products that contain it. Where it turns conditional is the very young, and this is worth getting right because two different chemicals share the name. The cosmetic preservative is chlorphenesin, CAS 104-29-0. A separate muscle-relaxant drug, chlorphenesin carbamate, can slow the nervous system and breathing, but that is the drug, not the preservative, and the CIR panel concluded the dermal use of the cosmetic ingredient cannot reach the blood levels needed for those effects. The caution that remains is specific: in 2008 the FDA warned against a nipple cream that contained chlorphenesin and phenoxyethanol and was not meant to be wiped off before nursing, since a baby could swallow it directly. No infant injuries were ever reported, and the product was pulled. Regulators also split on it, which is the signal worth weighing: Europe and the United States permit it at 0.3 percent, while Japan restricts it over allergy concerns. So for an everyday adult moisturizer this is a low-risk preservative; the place to pause is products for nursing, infants, or the diaper area, where gentler options exist.