What Is Propylene Glycol?

What is propylene glycol?

Propylene glycol is a non-toxic, liquid additive that absorbs water. As a humectant, emollient, and preservative, propylene glycol holds moisture while preventing mold in certain medicines, cosmetics, and foods. As a solvent, it helps improve the texture and consistency of foods, drugs, paints, and more. It is also used to create artificial smoke.

Propylene glycol is typically odorless, tasteless, and colorless, and its texture is somewhat oily or syrupy. It is generally considered a safe chemical, according to the CDC, although frequent exposure to it has been linked to skin irritation.

What is propylene glycol used for?

Propylene glycol is used in a variety of products and manufacturing processes.

Food industry

The use of propylene glycol in foods is common and generally considered to be safe. When consumed, propylene glycol breaks down in the body quite quickly—within 48 hours—and is changed to an energy source.

Unlike similar substances like ethylene glycol, propylene glycol does not form harmful crystals as it’s being broken down in the body. Amounts not broken down and metabolized are passed out of the body in urine.

Pharmaceuticals

Pharma grade propylene glycol is widely used as a solvent in drug manufacturing. This means it dissolves other substances (usually solids) without changing their fundamental structure or composition.

Propylene glycol is also used as a carrier in drug formulations. Active ingredients can be formulated in it and delivered to the body through it. Finally, it is used to dilute and stabilize medicines.

Propylene glycol can be used in different forms of drugs, including oral drugs like capsules and tablets, topical drugs like creams and gels, and intravenous (injected) drugs.

Cosmetics

Cosmetic grade propylene glycol is a common ingredient in cosmetic, personal, and skin care products. It is in anywhere from 26.4% to 37.8% of registered personal care products.3 Propylene glycol is a versatile substance that carries out many functions in the product formulations in which it is included. Some of these functions include the following:

Humectant: Humectants are included in cosmetic and skin care products for their moisturizing abilities. Propylene glycol works as a humectant by attracting moisture to the skin and consequently hydrating and moisturizing it.

Solvent: Propylene glycol is used to dissolve substances in a product formulation to get them to mix and work together properly. It also acts as the carrier for active ingredients.

Emollient: Emollients are ingredients that soothe and hydrate the skin. They’re instrumental in skin care products for treating dry skin. Propylene glycol is an emollient because it forms an oily layer on the skin and prevents water loss.

Viscosity control: Propylene glycol reduces the thickness of cosmetic formulations and products. This helps them spread across the skin better, and it also improves how well the products are absorbed.

Preservative: Propylene glycol is often used in combination with other chemicals as a preservative in cosmetic and skin care products.