Let us clear things up for you.
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Vaseline made it famous, but you’ll find petrolatum in other moisturizers too. It’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. “I wouldn’t use it in the morning, because you wouldn’t put makeup over it,” says Dr. Hirsch. Click here to find more nighttime habits of people with great skin.
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Because they’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. “Look for something that’s oil-free—so no mineral oil, no silicones,” she says. “It’s not specifically what’s in in, it’s more what to stay away from. You want a lighter moisturizer, something that won’t clog pores or cause an occlusive barrier.” But if you’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 they’ll trap moisture that would otherwise evaporate out, says Dr. Hirsch. These essential oils take years off your skin.
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Lanolin, an oil extracted from sheep’s wool, is an occlusive, but it also acts like an emollient, meaning it can help fill in the space between cells. “If 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,” says Dr. West.