Propylene Glycol is the next ingredient listed on the back of the box. Propylene Glycol is a colorless, thick, moisture absorbing liquid often used as an antifreeze and in brake fluid. But because of its innate ability to retain moisture, it is also often used in skin lotion and cosmetics.

Propylene Glycol is also the main ingredient used in most moisturizers because it tends to not only retain its moisture, but can even help prevent things from losing their moisture. Things like massage and fragrance oils, as well as many tobacco products, use propylene glycol to help stabilize the moisture content, so they do not dry out too quickly.

Because the toxic nature of Propylene Glycol is so low, it is safe to use in products intended for humans. It can become toxic when extremely large quantities are used, but in small quantities it is imperceptible to the body. Because of this, the Food and Drug Administration have declared Propylene Glycol as “Generally recognized as safe” for human consumption. So, despite there being quite a lot of information out there on the internet claiming that Propylene Glycol is not at all safe to be used and can in fact lead to liver problems and kidney malfunctions – you should ignore such facts. The FDA would not have concluded that Propylene Glycol was safe in any way if after their extensive research on the subject they had come across any such conclusions about the chemical.

As for hair, Propylene Glycol is again used as a moisturizer because again, it retains the moisture content. Which means that the use of Propylene Glycol in the shampoo or conditioner helps prevent hair from losing its moisture throughout the day.