Why do I get itchy skin in the winter?

Q “It happens every winter, like clockwork. I get that the house is drier with the furnace on 24/7, but why does that make my skin so itchy? I’d like to understand what is going on at a microscopic level and what I can do about it. No matter how many creams I buy and slather on, it just keeps coming back.”

Scratching in Scarborough

A I love nitty-gritty questions like these, not least because it means I get to ring up a doctor and ask them in detail about their work, especially when it comes to dermatology. All the Latin makes me giddy as I’m still a nerdy 10th grader at heart. It also makes me humble: there is so much I don’t know about how the human body works and so much I make up to fill in the yawning gaps of knowledge.

We all do this. A great example, says dermatologist Dr. Lisa Kellett, is the myth that we are “dehydrated” when our skin is dry and itchy. The fact is, we might well be dehydrated, but that is not going to show up in the form of dry skin. “Skin does not get dehydrated. An apple gets dehydrated. That is not the right term,” says Kellett, who runs the Toronto medical and esthetic skin clinic DLK on Avenue. “What you have is what we call transdermal water loss on the surface of the skin.”

Where you see flakiness, that is indicative of water loss. “On the

stratum corneum, or the upper layer of skin, the barrier that is supposed to protect us has been breached,” she said. “That causes the sensation of itchiness.” The correct term for itchiness, by the way, is “pruritus.”

If your itching is really bad and persistent, Kellett says you should make an appointment with your family doctor to eliminate systemic problems. “There is a very long list of causes of pruritus, and you want to make sure it is not thyroid or a systemic disease like lymphoma,” she said. “Get it checked out if it is accompanied by weight loss, night sweats and chills — those are not good things.”

Even if your itching is not linked to a serious health problem, Kellett thinks the discomfort of itching is not something to be minimized. “Itching can be worse than pain,” she said. “It can keep you up at night. In quality-of-life studies it has shown to be very debilitating.” She is talking about afflictions such as eczema, a.k.a. atopic dermatitis (dermatitis refers to skin irritation and there are 15 different types of it; atopic is one).

Allergies may be a factor, as itching can be caused by histamines, chemicals released by the body during allergic reactions. If so, Kellett says using an over-the-counter antihistamine might help.

If you find you have simple, runof-the-mill itchy skin caused by cold winter weather, and wind chapping outside and forced air inside, Kellett is pleased to report there are quite simple and inexpensive fixes for it. “I’m a purist; I believe you should start with simple things,” she said.

First of all, use a humidifier, especially in the bedroom considering how much of your time you spend there. “Next, take a bath and put some oil in the water. Aveeno has a good one,” she said. “After you get out of the bath, don’t dry off with a towel: put moisturizer on your wet skin, then put on a robe and let your skin air dry. It will increase absorption of the moisturizer.”

Kellett recommends simple, inexpensive moisturizers that are free of fragrance (which can cause irritation and allergic reactions), such as Aveeno, Cetaphil and Eucerin.

Creams, she says, are more occlu- sive than lotions, offering a thicker layer of protection on the barrier of the skin. “Vaseline is the most occlusive,” she said, adding that it definitely has its uses in skin care, in moderation.

TikTok has popularized the “slug- ging” trend, in which people put a thick layer of Vaseline on their skin overnight, but Kellett says this might not be the best idea. “I’ve seen people who do that end up with perioral dermatitis,” she said, referring to another one of the 15 types of dermatitis, which presents as little bumps around the mouth.

Having said all of that, “a moisturizer on its own doesn’t really do it because the cause is transdermal water loss,” Kellett said. You have to treat what is causing the itch. It’s tiny tears in the dermal layer that lead to moisture loss and prevention is the best medicine. For instance, if your hands are dry and itchy, wearing gloves is a simple way to keep your barrier layer intact.

I’m excited by the simplicity of Kellett’s tips and tricks, and have already hauled my humidifiers out of the basement, where they have sat gathering dust since my kids were little. I’ll add them to a winter regimen I’ve had success with myself this winter: the Xémose line by French skin care line Uriage, which is designed to soothe itchy skin.

I rang up Dr. Toni Ionesco, the dermatologist in France who works on the line, to delve even deeper into winter itchiness. “In the epidermis, the natural ‘cement’ between the skin cells, which is made of lipids (ceramides, sterols), is weakened by the cold — that is why the water from the epidermis is lost more easily when it’s cold,” he explained. “Skin dried from cold temperatures will be prone to itch, to tingling, to a sensation of tensed skin.”

Uriage’s Xémose line features a patented ingredient called Chronoxine, which is an amide (an organic compound related to ammonia). “It induces human skin cells to produce natural soothing substances such as lipoxins and maresin,” Ionesco said. (I’m not going to attempt to translate those terms.) “These two natural substances reduce inflammation and in consequence decrease the itch.”

Sounds great, but basically I’m a fan of the line’s Anti-Itch Oil balm because I love the nongreasy balmto-oil finish of the product. I get claustrophobic with too much or too heavy product on my skin. So I won’t be slugging anytime soon, but I definitely will be adding oil to my baths, applying moisturizer onto wet skin and walking around air drying as humidifiers blast moisture into every room.

Thank you for coming to my winter skin science basics class. I sincerely wish you an itch-free day.