Glycerin in skincare: what it does, benefits and is it safe?

Glycerin moisturizes your skin. It is a humectant, a substance that attracts water, and your skin already contains it naturally. In creams and serums it pulls water into the outer layer of skin and helps keep it there, so dry, rough skin feels smoother and more comfortable. It is gentle, rarely causes reactions and suits all skin types.

What glycerin does for your skin

Glycerin (also called glycerol) is a small, clear, slightly sweet and syrupy liquid. Chemically it is a simple alcohol with three water-loving groups, which is why it mixes so easily with water and holds on to it. It isn't a drying alcohol like the ethanol in some toners. It has been used in skin products for many decades, and your own skin uses glycerol as part of its natural hydration system.

A widely cited dermatology review of glycerol and the skin describes several effects of applying it:

• Better hydration of the outer skin layer, the stratum corneum.
• Support for the skin barrier, the layer that keeps water in and irritants out.
• Softer, more flexible skin, which is why rough, flaky patches look smoother.
• Protection against irritation from some harsh substances.
• Help with normal shedding: it supports the breakdown of the "glue" between old skin cells, so dry flakes come away more easily.

The same review notes that glycerol-containing products help in conditions with dry skin and a weakened barrier, such as atopic eczema and dry winter skin. A Cochrane review of moisturizers for eczema found that in one study more people using a glycerol cream noticed their skin improve than people using a cream without it. The difference was modest, so treat glycerin as a dependable helper, not a cure.

Glycerin for dry skin and a damaged barrier

The American Academy of Dermatology lists glycerin among the ingredients to look for in a cream or ointment for dry skin. It works best as part of a balanced moisturizer: glycerin draws water in, while oils, butters and occlusives such as petrolatum or dimethicone slow down evaporation. That is why so many good moisturizers combine glycerin with ceramides, shea butter or squalane.

1. Wash with a gentle cleanser and lukewarm water.
2. Pat your skin lightly, leaving it slightly damp.
3. Apply a moisturizer with glycerin right away, then sunscreen in the morning.
4. Reapply on very dry areas whenever your skin feels tight.

Applying moisturizer to damp skin is standard dermatologist advice and makes sense for a humectant, because there is water on hand to hold. For a full routine, see our guides to dry skin on your face and repairing your skin barrier.

Glycerin vs hyaluronic acid

Both are humectants and they often appear in the same product. The main differences come down to size and feel.

You don't need to choose. Glycerin is the workhorse found in most moisturizers, and a hyaluronic acid serum is an optional extra if you like the texture. Neither replaces a moisturizer that seals water in.

Why glycerin is near the top of so many labels

Ingredient lists go from the highest to the lowest amount, at least for everything above 1%. Glycerin often sits second, right after water (Aqua), because it is cheap, effective and easy to formulate with. Besides moisturizing, it helps dissolve other ingredients and adjusts texture. When the Cosmetic Ingredient Review (CIR), the US expert panel that assesses cosmetic ingredients, evaluated it, glycerin was the third most frequently reported ingredient in cosmetics after water and fragrance, used in more than 15,000 products.

Brands rarely state how much glycerin a product contains. The CIR report lists use in leave-on products at up to 79.2% and in rinse-off products at up to 99.4%. More isn't automatically better: very high levels can feel sticky, so many formulas balance it with other ingredients. Learn how to judge a formula by its first few ingredients in our guide to reading cosmetic ingredient labels.

Is glycerin safe for skin?

Yes. The CIR expert panel concluded that glycerin is safe as a cosmetic ingredient at the way it is currently used. The panel noted that glycerin occurs naturally in human tissues, including the skin and blood, has low toxicity, and was not an irritant or sensitizer in the tests it reviewed. A moisturizer with 65.9% glycerin did not sensitize volunteers in a patch study.

Allergy is possible but rare. The CIR report describes a single case of a woman whose eczema was traced to glycerin in her hand cream and cleared when she avoided it. If a glycerin product irritates you, another ingredient in the formula, such as fragrance, is usually the more likely cause. Our sensitive skin guide explains how to narrow it down.

Is glycerin comedogenic, and is it OK for oily skin?

Glycerin is water-soluble and contains no oil, and it is not known as a pore-clogging ingredient. It is a good choice for oily and acne-prone skin, which can still be dehydrated. Look for light, oil-free gels and lotions with glycerin, as described in our oily skin guide.

Vegetable vs synthetic glycerin

Natural glycerin is a byproduct of turning fats and oils into fatty acids or their esters, the same chemistry behind soap and biodiesel. It can come from plant oils or animal fats. Synthetic glycerin is made by other routes, often from petrochemical starting materials such as propylene oxide or allyl chloride. Once purified, both are the same molecule, and safety tests found neither natural nor synthetic glycerin to be sensitizing.

Glycerin myths

• "It pulls water out of your skin in dry air." The worry is that a humectant draws water from deeper skin when the air is dry. Research suggests glycerin still helps in dry conditions, partly by keeping the skin's lipids flexible, and a moisturizer that seals the skin makes this a non-issue in practice.
• "It's an alcohol, so it dries skin." Glycerin is technically an alcohol, but it is a moisturizing one, nothing like the drying ethanol listed as alcohol or alcohol denat.
• "Cheap means it doesn't work." Glycerin is inexpensive because it is produced on a huge scale, yet it is one of the best-studied moisturizing ingredients.
• "Pure glycerin is the best moisturizer." Undiluted glycerin is thick and sticky. It works better as part of a balanced formula.