A type of alcohol, butylene glycol is made from corn, as per Healthline. It works to foster key processes that cosmetics need, such as preventing ingredients from sticking and allowing for a smooth and flowing consistency, which is vital for foundation and concealers, as well as the other cosmetics that use it. The compound prevents makeup and products from clumping, and it is also added to food.

In general, butylene glycol doesn't pose a high risk and isn't considered to be unsafe. It typically doesn't cause irritation or dryness in most people. Skin Deep rates butylene glycol as a 1 which is the best rating the website gives, with 10 being the worst.

Of course, any ingredient has the potential to cause an allergic reaction in certain people so it's always best to do a patch test before using any new makeup or skincare product. This is especially true if you have sensitive skin.