Propylene glycol, a common ingredient in skincare products, can cause two types of skin problems: irritant reactions (like redness or burning) and allergic sensitization (where your skin becomes allergic to it over time). While it's useful as a vehicle for delivering other ingredients, it's not suitable for everyone—especially those with sensitive skin.

The researchers reviewed existing scientific literature on propylene glycol to document patterns of adverse skin reactions and identify which people are most at risk.

Funding not disclosed in abstract