Propylene glycol is an organic compound that is used in a variety of products, including antifreeze, food coloring, and food preservatives. It is also an effective humectant, meaning it helps to keep things moist. It is a colorless, odorless, nearly tasteless liquid that is used as a base in many cosmetic products, including lotions, shampoos, and makeup. It is also used in a variety of industrial applications, including as a coolant and lubricant. Propylene glycol is generally regarded as safe and non-toxic, but it can cause skin irritation in some people.