Having dry or dehydrated skin can be the absolute worst—take it from someone who knows. Lately, my skin has been so dehydrated that I’ve had to switch up my foundation options because some of them are far too drying for everyday wear. It’s definitely frustrating, but if you also struggle with dryness, you’ve come to the right place.

I’ve recently learned a few things when it comes to skin that’s dry vs. dehydrated, and that’s all thanks to celebrity esthetician Renée Rouleau. I asked Rouleau to share her knowledge on dryness, dehydration, the skin’s moisture barrier, and more. She also shared the best hydrating serum to help keep your skin nourished. Keep reading—there’s lots of important knowledge ahead. 

Dry skin lacks natural oils and is something you’re genetically predisposed to,” she says. “We also become more prone to it as we age. Dehydrated skin lacks water and is a temporary condition that anyone can have. Both dryness and dehydration can disrupt barrier function.” It’s important to know the difference between the two and how each plays a role in the function of your moisture barrier. 

There are a few different ways your skin could be dehydrated, and they can cause some real damage to your moisture barrier, something that Rouleau also says is the main cause of most skincare issues: “In my 30-plus years of experience, I have seen that pretty much every skin concern can be traced back to (or exacerbated by) a damaged moisture barrier. There are so many conditions that indicate a damaged barrier—redness, dryness, irritation, increased breakouts… The list goes on. The moisture barrier acts as your skin’s personal bodyguard, keeping the good stuff in and the bad stuff out. When it’s compromised, small cracks appear, allowing moisture to escape and irritants to enter, leading to all of these issues!” 

If you’re noticing any of these issues and your skin has become increasingly dry, Rouleau has a few extra tips. Use a moisturizer that mimics the skin’s barrier structure with ingredients like ceramides, phospholipids, shea butter, and plant oils such as jojoba,” she says. “You can also use an essence to help reintroduce hydration into the skin.” Another great way to boost hydration in the skin is by adding a deeply hydrating serum to your routine so that your skin can begin to repair itself and get the nutrients it needs. For a rec from Rouleau along with my own favorites, keep scrolling.

“My Skin Drink Concentrate is a great option to infuse hydration back into the skin—I like to say it’s like a tall glass of water for your skin!” Rouleau says.

With two forms of pure hyaluronic acid and vitamin B5, this serum from La Roche-Posay locks in moisture and helps repair the skin within hours of application.

Drunk Elephant’s B-Hydra is a winter favorite of mine. It contains pineapple ceramides to help improve the appearance of skin’s texture, sodium hyaluronate for deeper hydration, and vitamin B5 to help the skin attract even more moisture throughout the day, improving barrier function.

Neutrogena’s Hydro Boost is a classic drugstore serum that gets the job done. I’ve used it on and off for years if I’m ever in need of some extra hydration, and it always does the trick.

CeraVe’s serum is formulated with the brand’s highest concentration of hyaluronic acid to help the skin retain more moisture and appear smoother.

This deeply conditioning serum from Biba Los Angeles is loved by celebs like Hailey Bieber. I recently started using it myself, and it provides so much extra hydration to my skin and literally firms it overnight. As a bonus, it also gives you a serious glow.

This weightless, noncomedogenic serum from Summer Fridays is great for those who are acne prone. It contains a hefty dose of glycerin, hyaluronic acid, colloidal oatmeal, aloe, and squalane to deliver extra moisture and support the barrier without clogging pores.

If you’ve been dealing with some barrier damage, this serum from Skinfix is your ticket. It’s supercharged with a triple-lipid complex, a plumping seaweed hyaluronate blend, and a peony-root complex to support the skin barrier and relieve dryness.

Amplify your skin’s natural hyaluronic acid levels with this intensely hydrating serum from SkinCeuticals. The unique formula contains a high concentration of HA along with Proxylane and botanical extract, which improve fine lines and overall skin plumpness.

L’Oréal’s Revitalift contains both vitamin C and hyaluronic acid to give the skin a dewy, hydrated glow.

Touted as a favorite by skincare expert Hyram Yarbro, this barrier-protecting serum nourishes dry and dehydrated skin with a blend of oils and rebalancing actives to restore damaged skin. It will even help clear breakouts and soothe skin that’s both dry and acne prone.

This formula contains Avène’s soothing thermal spring water along with glycerin and lipids that help reduce water loss.

This serum from Cosmedix helps to minimize the signs of aging and rejuvenates the complexion with extra hydration. It contains potent growth factors, and it deep-conditions the skin and protects against environmental stress with ingredients like Japanese orchid stem cell extract, jojoba esters, and panthenol.

SkinMedica’s serum provides deep hydration for eight continuous hours. It’s also packed with vitamin E and peptides to protect the skin from premature aging.

This serum is rich in omega 3, 6, and 9 to support the skin’s natural barrier and relieve any tightness or dryness.

Up Next: Will “Skin Flooding” Actually Curb Your Dry Skin? Here’s What Derms Have to Say