My hand lotion dispenser gets a workout in the winter.

I wash my hands a lot to prevent whatever virus is making the rounds of my neighborhood. Afterward, I lotion up to prevent the dry skin that often seems to accompany cold weather.

And it’s not just hand washing that may lead to dry skin. In a study of German hairdressers, who presumably have similar routines regardless of season, researchers noticed more complaints about dry and irritated skin during cold winter months.

What is it about winter that causes skin to be more dry?

“It’s multifactorial,” says Daniela Kroshinsky, a Harvard dermatologist. Humidity is a big reason. Outdoors, the cold air holds less moisture. Indoors, heating systems also dry out the air.

If you take long, hot showers, that will add to the problem because you’re washing away some of the natural oils in your skin. Harsh soaps, Kroshinsky says, can strip even more oils out.

“But soap is not the main thing,” she says. “Humidifiers are wonderful.”

Studies on human skin function found the top layers of skin holds less water in low-humidity conditions.

If you want to humidify your home, Kroshinsky recommends a high capacity machine. “Smaller units probably don’t change the humidity level effectively,” she says.

A humidity gauge will ascertain that the machine is having an effect — 45 to 55 percent relative humidity is a typical target.

The main problem with dry skin is that it is uncomfortable. And sometimes kind of gross. My lips may crack and I can shake dander out of my clothes at the end of the day.

A review of the scientific literature on climatic conditions found this general truth: Low humidity and low temperatures reduce the skin’s capacity to serve as a barrier and increase the risk of dermatitis — itchy, dry and often inflamed skin.

Patients with atopic dermatitis — the most common form of eczema with its characteristic red, itchy skin — are particularly sensitive to winter dryness and can experience flare-ups.

Patients complaining of itchy skin are not uncommon beginning in November or December, says Gary LeRoy, a family physician in Dayton, Ohio, who is president of the American Academy of Family Physicians.

“When did you turn on your heat in your house and close all your windows? Do you take really hot baths or showers? Do you pat or rub dry? Rubbing can exfoliate the skin and can add to drying out,” he says.

LeRoy recommends taking showers that aren’t too long or too hot, patting yourself dry and applying moisturizer while your skin is still damp. Also, “an oatmeal bath can help with itchy sensation,” he says.

The easiest route to managing dry skin in winter is to use a moisturizer. They come in varying packaging — pump or pour lotions, creams in a tube or jar, and ointments, such as petroleum jelly — and contain a dizzying array of ingredients.

They don’t actually add water to your skin. Rather, they keep water from escaping. Some substances, such as shea butter and lanolin, which are emollients, are intended to make your skin feel softer.

LeRoy says lotions with a lactic acid base are “pretty doggone good.” Other ingredients to look for are salicylic acid, glycolic acid, and urea.

Kroshinsky says helpful ingredients include ceramides, glycerin and hyaluronic acid.

Ceramides are naturally occurring compounds in the skin that impede water loss. Both urea and lactic acid work in part by stimulating the skin to make more ceramides.

One study compared six commercially available moisturizers that contain different mixes of therapeutic agents on the skin of 80 people with moderately or severely dry skin. Applied twice a day for four weeks, all the products improved symptoms.

The researchers concluded that “consistent and regular moisturizer use is much more important than the moisturizer’s particular formulation.”

Kroshinsky agrees. She tells her patients to choose a moisturizer that they will use: “If you don’t like the feel or the smell, that’s not good. Because you have to actually use it.”

Moisturizing twice a day seems to be the ideal treatment. “You’ll get the most bang for your buck after the shower,” Kroshinsky says.

That is because the lotion or cream will trap moisture gained from your shower. Plus, she says, cream-based moisturizers go on easier when your skin is damp and feels less greasy.

Both doctors agree that it’s best to avoid fragrances and color dyes, which can be irritating. Beware: a lotion labeled “fragrance-free” means just that, while “unscented” lotions are formulated to not have a noticeable odor, but may still contain fragrance compounds.

When should you see a doctor for dry skin? “When you become concerned about it,” LeRoy says. “Because it’s compromising your lifestyle or common fixes aren’t helping.”

Other things that should be checked out are rashes that won’t go away or are getting worse, and any sign of infection — skin that’s hot to the touch, painful or weeping.

Kroshinsky says a good dermatologist will check for other causes of dry skin. Maybe it’s not just winter drying out your skin. It could be a health condition or your medication.

Some people are more sensitive to changes in climate, especially the very young and the very old.

“As we age, the oil components of our skin diminish,” Kroshinsky says. Also, skin is thinner in older people.