Ethylhexylglycerin
In plain terms
A skin-conditioning ingredient and preservative booster that also fights odor. Low-risk for most, with one thing worth knowing: it is a recognized though uncommon cause of allergic reactions, and it often appears in products marketed as gentle or preservative-free.
What the evidence shows
Ethylhexylglycerin is an alkyl glyceryl ether used to soften skin, deodorize by slowing odor-causing bacteria, and boost the preservative system so formulas can rely on less of stronger preservatives. The CIR panel and predictive human patch tests at use levels found no irritation or sensitization, and it carries a low hazard profile. The one point worth stating plainly is allergy. Ethylhexylglycerin is a recognized contact allergen, but an uncommon one: across large patch-test populations it tests positive in roughly 0.1 to 0.3 percent of people, a rate the dermatology literature places alongside parabens, benzyl alcohol, and phenoxyethanol. When reactions do happen they are usually relevant, most often on the face from a moisturizer, sunscreen, or deodorant, and they turn up often enough in products advertised as hypoallergenic or preservative-free that the label claim is no guarantee. So for the large majority this is a low-risk, useful ingredient; for the small group who react, it is worth knowing as a hidden trigger in otherwise gentle products. If you get unexplained facial dermatitis from a cream you considered safe, this is one to have patch-tested.
On the label
Listed as ethylhexylglycerin or octoxyglycerin, usually next to phenoxyethanol. No reason to avoid it as a precaution. But if you keep reacting to leave-on creams, sunscreens, or deodorants, including ones labeled gentle or preservative-free, ask a dermatologist to patch-test ethylhexylglycerin 5 percent.