It’s that time of the year again. We’re gathering with families and Marcus Eriksonfriends, seeing people we may not have spent time with all year. The weather is getting colder outside our windows. And for many of us, we find ourselves plagued with dry skin. Oof.

But what exactly is causing this change in your skin?

Understanding the cause can help you better understand how you go about treating skin dryness. We talked to Dr. Dina Strachan, a board-certified dermatologist and the director of Aglow Dermatology in New York City to give you answers.

What causes dry skin?

It probably sounds obvious, but you get dry skin when there isn’t enough water in your skin. What may not be so obvious, however, is how this happens.

Dry skin primarily occurs because of damage to the lipid skin barrier. This barrier protects the water in your skin from evaporating. When it’s disrupted, the water can escape out of your body and into the air.

Does drinking water help dry skin?

Dry skin can occur if you don’t have enough water. However, this is less likely to be the cause given you would need to be severely dehydrated. “What people are experiencing isn’t going to be solved by drinking more water. People aren’t necessarily dehydrated like that,” explains Strachan. “It’s more what’s happening at the skin barrier level.”

What triggers disruption to the skin barrier?

There are various reasons your skin barrier may be disrupted. Showering or washing your hands too often, hot water and harsh soaps can strip the natural oils from your skin. According to Healthline, other causes include allergens and irritants, too much sun exposure, over-exfoliation, steroids and stress.

Dry air and artificial heat can also lead to dry skin. This is because water molecules move from areas of higher water concentration to areas of lower water concentration. So, dry air pulls moisture from your skin in an attempt to reach equilibrium. A strong skin barrier will help prevent this movement.

When is dry skin a sign of something more serious?

Taking care of your skin is an important part of your health. “Having a disrupted skin barrier and dry skin is not actually a harmless thing,” says Strachan. “Its purpose is to protect you.” Your skin barrier not only retains moisture but also works to keep infection-causing bacteria out of your body. Strachan adds, “Part of health is having things where they’re supposed to be and not where it’s supposed to be.”

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