Derms don’t go a day without recommending ceramides, but what are they exactly?

Ask any skin-care pro which ingredient should be a top priority in your moisturizer, and you’re next to certain to hear a lot about ceramides. No lie: three consecutive derms heralded this ceramide-rich $16 moisturizer as a dry skin savior. Aside from being a word that rolls of the tongue of derms all the time (and that feels damn near impossible to spell, TBH) what are ceramides and why are they so important for keeping your skin hydrated?

Ceramides are lipids that occur naturally in your skin, and make up more than 50 percent of it, according to Sheel Desai Solomon, MD, a Cary, NC dermatologist. If you think of your skin cells as bricks, the “mortar” in between them is filled with ceramides (plus cholesterol and some other fatty acids), which Rachel Nazarian, MD, a New York City dermatologist tells me is the “first line of defense” in protecting your skin from the elements. “It helps preserve the barriers of the skin and lock in moisture as well as shielding the skin from pollutants,” adds Dr. Solomon.

When all of this is intact, moisture stays within skin to keep it hydrated and protected, but when it’s not, that’s when transepidermal water loss (aka when the water gets sucked out of your skin by the environment) happens. This can leave your skin feeling dry and inflamed, and it can make you more at risk for sensitivity issues like itchiness and eczema.

All of this is why topical ceramides are so important (especially as the dry season approaches). They flood your skin with ceramides to replace what’s missing and help restore the skin barrier. “They’re popular in cosmetics because they help smooth skin,” says Dr. Solomon, adding that they help protect from aggressors like pollutants, infrared, and heat. You’ll find them in all sorts of different products from cleansers to toners to serums, but they’re most important to use in your moisturizer as the last layer that locks everything in.

Even if you’re not dealing with dryness or sensitivity right issues now, eventually, you might be. In the same way that our collagen and elastin levels dip as we get older, so do our ceramide levels. According to New York City dermatologist Melissa Levin, MD, you lose 40 percent of your skin’s naturally occurring ceramides by your 30s, and 60 percent by your 40s, which means you’ll be more prone to irritation and dry skin as you age. In order to set yourself up to have the best-functioning skin possible, Dr. Levin suggests slathering these onto your complexion ASAP.

“The key is to be consistent with your application,” says Dr. Solomon. “The results will not come overnight. If you are using it to help prepare your skin, making it more resilient against aging, you will see that with consistent use of the lipid you will get the best results.” Here, derms share their top choices for making sure you’re getting enough of those building blocks in your routine.

SkinCeuticals Triple Lipid Restore, $128

This lipid-enriching cream is packed with two percent ceramides, four percent cholesterol, and two percent fatty acids to give your skin all the good stuff it needs on the reg.

CeraVe Daily Moisturizing Lotion, $10

Derms are in love with this $10 drugstore pick, and all three MDs who were interviewed for this story called it out as one of their faves. It’s lightweight and oil-free, which means it’s the perfect pick if you hate goopy creams or tend toward oily skin.

Glossier Priming Moisturizer Rich, $35

“This cream is rich in ceramides and fatty acids and it reinforces the skin barrier while locking in moisture over time,” says Dr. Solomon. It’s nice and thick—like marshmallow fluff, without the stickiness—and will give your skin a deep drink of hydration whenever you apply.

Eucerin Advanced Repair Cream, $12

This moisturizer is a dream for extra-dry skin. It promises 48 hours worth of hydration, and is recommended by derms for helping to repair sensitive skin issues. It’s one of those drugstore moisturizers that genuinely feels like a luxury to apply, especially if you love a heavier texture.

EltaMD PM Moisturizer, $28

In addition to ceramides, this nighttime moisturizer also offers a triple threat of peptides, niacinamides and antioxidants to keep your skin barrier feeling its best and brightest (and strongest).

Another ingredient that’s hard to spell but great for dry skin? Hyaluronic acid. Plus, derms weigh in on whether you should be using a moisturizer or an oil to keep your face hydrated.