Propylene Glycol has many functions and is used in a multitude of skincare products for its versatility. Here are its main functions:

Attracts water: Zeichner says at low concentrations, Propylene Glycol acts like a humectant, which means it binds water and pulls in hydration to the outer skin layer. When used in cosmetic products, it helps give the skin a hydrated, dewy appearance.

Boosts other ingredients: Because of its binding properties, Propylene Glycol can enhance the delivery of other active ingredients into the skin.

Lightly moisturizes: Herrmann adds that as a humectant, it also offers moisturizing benefits and smoothes the skin with a light, non-sticky feel.

Addresses visible signs of aging: The humectant property also makes it a useful ingredient for dry or aged skin. "As we age, our skin loses a component called Natural Moisturizing Factor (NMF) and subsequently dries out, which emphasizes wrinkles and contributes to flaking and roughness," Herrmann says. " Propylene Glycol helps bind water from the environment, helping to counter the water loss that accompanies aging."

Enhances penetration: Zeichner says it helps the active ingredients of cosmetics penetrate through the skin, which in turn makes them more effective.

Prevents water loss: As an emollient, Propylene Glycol forms a protective film on the skin that prevents water loss and helps to smooth and soften skin, according to Herrmann.

Is safe for acne-prone skin: Because it’s not oily, Herrmann says it’s also ideal for those with acne.

Helps lessen the appearance of spots over time: Due to its moisturizing properties, Propylene Glycol nourishes the skin, helping to lessen the appearance of marks and acne spots.

Side Effects of Propylene Glycol

While Propylene Glycol actually should be avoided for some people, it's not for the scary reasons you might have read about online. Because Propylene Glycol is derived from petroleum, many have concerns that it is carcinogenic and can be toxic when used in skincare. But according to Zeichner, cosmetic-grade petrolatum is different than commercial petroleum and is not carcinogenic, and similarly, neither is propylene glycol.