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10 Confusing Moisturizer Ingredients, Decoded

Let us clear things up for you.

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Petrolatum

Vaseline made it famous, but youโ€™ll find petrolatum in other moisturizers too. Itโ€™s known as an occlusive, which is an ingredient that forms a barrier on the outermost layer of your skin to hold water in, sort of like a topcoat of nail polish, says Ranella Hirsch, MD, FAAD, a dermatologist in Cambridge, Massachusetts. Petrolatum is a great choice for trapping in the moist air after a steamy shower at night, but it could be too greasy to use during the day. โ€œI wouldnโ€™t use it in the morning, because you wouldnโ€™t put makeup over it,โ€ says Dr. Hirsch. Click here to find more nighttime habits of people with great skin.

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Oils

Because theyโ€™re occlusive, oils like mineral, coconut, and avocado oil sit on top of the skin while sealing in moisture. But that barrier could be bad news for acne-prone skin, says Tina West, MD, PC, dermatologist and founder of skincare center The West Institute. โ€œLook for something thatโ€™s oil-freeโ€”so no mineral oil, no silicones,โ€ she says. โ€œItโ€™s not specifically whatโ€™s in in, itโ€™s more what to stay away from. You want a lighter moisturizer, something that wonโ€™t clog pores or cause an occlusive barrier.โ€ But if youโ€™re not worried about breakouts, occlusives could be useful if your skin is losing moisture outside factors, like dry air in a heated office, because theyโ€™ll trap moisture that would otherwise evaporate out, says Dr. Hirsch. These essential oils take years off your skin.

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Lanolin

Lanolin, an oil extracted from sheepโ€™s wool, is an occlusive, but it also acts like an emollient, meaning it can help fill in the space between cells. โ€œIf you think of them being like a cobblestone road, for example, the emollient will work by going between those little cracks and giving the skin a smoother texture,โ€ says Dr. West.

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Dimethicone

Both occlusive and emollient, dimethicone-based moisturizers feel nice to apply because its silicone base makes it feel more velvety. โ€œThey go on as a smooth product and donโ€™t create that thick gooiness,โ€ says Dr. Hirsch. โ€œYou want to use it in daytime because itโ€™s more cosmetically elegant.โ€ Check out these other skin care tips dermatologists use.

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Ceramides

Ceramides are a type of lipid, which are the molecules that appear naturally in your skin to help hold in water. Using them as a moisturizer ingredient can make that water retention more active, helped along by their fatty acids. โ€œWe call it waxy because it fills in the cracks between cells and the surface, but it wonโ€™t necessarily feel waxy,โ€ says Dr. West. This emollient is particularly helpful for people with eczema or very dry skin, she says.

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Glycerin

As a humectant, glycerin attracts water into skin cells, helping your skin bring in more moisture. โ€œYouโ€™re getting something that fundamentally attracts water to the skin rather than keeping it from getting lost,โ€ says Dr. Hirsch. Humectants like glycerin are ideal moisturizers if your skin is dry from traveling. Try out these morning habits of people with great skin.

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Hyaluronic acid

Another humectant, hyaluronic acid attracts moisture from the inner layer of skin cells, but it also attracts moisture from the air if itโ€™s humid enough, says Dr. West. Because it can evaporate, itโ€™s good to pair with an occlusive like dimethicone to help seal in the moisture, says Dr. Hirsch. โ€œGet a product like hyaluronic acid to absorb the water and then something to help retain the water for a double boost,โ€ she says. โ€œItโ€™s a wonderful trick when it gets very dry with the season change.โ€

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Propylene glycol

Some people avoid propylene glycol because it isnโ€™t natural, though thereโ€™s no evidence showing it will cause any harm. โ€œItโ€™s like how some people would rather buy something at Whole Foods than CVS because itโ€™s natural, but it doesnโ€™t necessarily mean itโ€™s better for you,โ€ says Dr. West. Seek out another humectant like hyaluronic acid if you try to avoid synthetic products, though propylene glycol is FDA-approved and shouldnโ€™t cause a reaction unless you happen to be allergic. This is the worst skin care advice dermatologists have ever heard.

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Urea

Urea is a humectant thatโ€™s also somewhat exfoliating, but that extra function might not be as good as it sounds. โ€œIn general, we donโ€™t lack exfoliationโ€”itโ€™s just a common myth thatโ€™s out there,โ€ says Dr. Hirsch. โ€œThe truth is most people could stop exfoliating, and no harm, no foul.โ€ You already scrub off some of those dead cells just by washing your face, and over-exfoliating could leave your skin raw. If you have particularly oily skin, though, you might want to a moisturizer with urea in your regimen, says Dr. Hirsch.

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Lactic acid

Lactic acid and urea both tend to be found in moisturizers marketed for people with extra dry skin because they help improve the skinโ€™s ability to hold water. โ€œTheyโ€™re good for people who need a molecule to help break down the skin barrier,โ€ says Dr. West. Click here to find out the best skincare routine for dry skin.

Marissa Laliberte
Marissa Laliberte-Simonian is a London-based associate editor with the global promotions team at WebMDโ€™s Medscape.com and was previously a staff writer for Reader's Digest. Her work has also appeared in Business Insider, Parents magazine, CreakyJoints, and the Baltimore Sun. You can find her on Instagram @marissasimonian.