Ask A Derm: What’s the Difference Between Dry and Dehydrated Skin?

woman touching her dry skin or dehydrated skin

In the dead of winter, the terms “dry” and “dehydrated” get thrown around a lot in conversations about skin. But, these two buzzwords aren’t one and the same. “They're not interchangeable,” notes Ranella Hirsch, MD, a board-certified dermatologist in Cambridge, Massachusetts. “I find that is singularly the biggest misconception.”

Dr. Hirsch, co-founder of Atolla® Skin Health System, says that dry skin is linked to genetics and oil production. Dehydration, on the other hand, stems from environmental situations, lifestyle choices, and superficial moisture in the very top level of the skin.

Beyond independent definitions and identifiers for each concern, people can certainly have both dry skin and dehydrated skin at the same time. However, solving each ailment requires different kinds of attention. Before slathering on moisturizers, serums, or consuming copious amounts of water, keep reading: Here, Dr. Hirsch breaks down how to figure out what’s going on with your skin, if you’re treating it correctly, and what your options are in terms of prevention.

What is dry skin?

Dry skin is a combination of several factors, many of which are genetic. One predetermined element is how much oil your skin produces, according to Dr. Hirsch. “Skin that is dry generally produces less oil than it would like to in an ideal world,” she explains. That oil is one of the binding elements that help hold the skin barrier together — without it, skin flakes. “Those flakes are individual bits of skin that are flaking up because there isn't enough glue to hold it all together,” adds Dr. Hirsch, who describes them as feeling rough on the skin. 

Typical areas you may notice dry skin include the insides of your arms and on the lower parts of legs. Dryness on the body can also include the lateral upper arms and flanks. Aside from that classic “ashy” appearance that makes skin look white or grey on the parched parts of your body, another indicator of dry skin is having more prominent-looking fine lines and wrinkles. 

What causes dry skin? How can I address it?

While having a skincare regimen is important, it won’t change your DNA: “Dry skin, fundamentally, is the type of skin you're born with,” says Dr. Hirsch. “It has to do with how much oil your skin actually produces. Dry skin can certainly be enhanced by your environment and some bad skincare choices, but it doesn’t change your skin type.” Although oil levels in your skin can’t really be modified, there are ways to prevent irritation from dry skin. “The skin needs a little bit of love and a little bit of TLC,” remarks Dr. Hirsch, who notes it’s important to be sensitive to things that strip your natural oils, like heat. “Specifically, a big one is overwashing the skin,” she adds. 

In terms of bathing, Dr. Hirsch says it’s best to avoid hot baths, take short and cool lukewarm showers, and towel off afterwards, but leave skin damp. She also recommends skipping out on items that are perfumed or scented. Beyond these measures, Dr. Hirsch suggests a specific ingredient to combat dryness issues. “Ceramides are really good at synthetically restoring what's naturally missing: that glue,” she says. “They help to function as a seal to keep moisture in deeper layers of the skin and [address] dryness.” We like SkinMedica® TNS® Ceramide Treatment Cream ($69), which hydrates and helps restore the skin’s barrier function.

What is dehydrated skin?

Unlike dry skin, which is hereditary, dehydrated skin can be controlled. Anyone, regardless of skin type, can get it — at any time. Many times it has to do with the amount of hydration in the top layers of the skin, says Dr. Hirsch. The moment those levels are depleted, skin can appear dull and feel tight, with fine lines more apparent on the face and body. 

What causes dehydrated skin? How can I prevent and treat it?

Dehydrated skin is all about the internal and external environments your skin is in. Dr. Hirsch says major offenders include UV rays. “You're having a tremendous amount of oxidants going into the skin, which are increasing free radicals, which are increasing damage and creating a lot of dehydration,” she points out. Limit sun exposure as much as possible — not only will it help keep your skin’s water levels high, but it will also help reduce your risk of skin cancer.

Other factors that trigger skin dehydration are air conditioning and central heating (which make the ambient air more comfortable for you, but not for your skin), using products that aren’t nourishing enough, general aging (which dries out the skin), and hot water.

Though dry skin and dehydrated skin are different, hot water is the enemy of both concerns due to its tendency to remove natural oils from skin. So, pump the brakes on your luxurious hot baths or showers. Also, “In some cities, the water tends to contain lime and other ingredients that can be very stripping as well,” warns Dr. Hirsch. She recommends quick “in and out” showers instead of long ones.

As for resolving already dehydrated skin, “The cheapest way to look younger and better is to put moisturizer on your face,” says Dr. Hirsch. You can also slather on serums, which are more able to deeply penetrate the skin due to their lighter molecular weight. Regarding ingredients to look for, the doctor recommends hyaluronic acid and peptides. The former is known for its ability to draw moisture into the skin, while peptides plump and hydrate. You can get both of them in Volition® Beauty Celery Green CreamTM with Hyaluronic Acid + Peptides ($55).

While mild exfoliation can be beneficial to sweep away dead skin, it’s important to avoid overdoing aggressive products that strip the skin. “More often than not, [patients] are using them too much,” says Dr. Hirsch. “That can really strip the moisture from skin and wind up causing you to be very dehydrated.”

Although we’d never advise you to skip out on drinking your eight, eight-ounce glasses of H₂O a day, chugging water is only part of the answer to treating and preventing dehydrated skin. It's important to be hydrated in your diet also. “There are lots of ways through food to also get fluids into your body in a good way,” she says. “I often encourage people to eat things like watermelon or cucumber, which are both packed with fluids.”

Regardless of the season, these identifiers and solutions can help combat both dry and/or dehydrated skin throughout the year.

Dr. Ranella Hirsch
Courtesy of Dr. Ranella Hirsch

Dr. Ranella Hirsch

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