What causes dry skin, and why is yours so dry?

Dry skin feels tight after washing, looks dull or flaky, and can itch. MedlinePlus, the health site of the U.S. National Library of Medicine, says dry skin occurs when your skin loses too much water and oil, and that it can affect anyone at any age. The medical name is xerosis. This guide goes through the causes that sources name, from the ones you can change today to the ones that need a doctor. To check whether your skin is dry or oily overall, see how to find your skin type.

What dry skin is

Your skin's outer layer holds water in, and your oil glands make an oil that keeps the surface soft. The American Academy of Dermatology (AAD) puts it simply: when skin loses water too quickly, it becomes dry. The AAD says you can often heal dry skin by making some changes, including moisturizing several times a day. It also says that when skin keeps losing water and cannot heal itself, it can become excessively dry.

MedlinePlus lists what you may notice: skin that is dry, scaly, itchy and red, with fine cracks. The AAD uses the word dehydrated for dry skin that has lost a lot of moisture, and dehydrated skin vs dry skin explains the difference between the terms. The AAD adds rough texture, flaking and peeling. In darker skin tones, the AAD says, the flaking, discoloration and rough texture show more than in lighter skin, and dry skin can look whitish or grayish.

Everyday causes you can change

Most dry skin comes from weather and habits. These are the causes the AAD and MedlinePlus name.

Cause	What the source says
Cold weather	The AAD says cold outdoor air holds less moisture, and research links it to excessively dry skin
Dry indoor air	MedlinePlus lists dry air from heating or cooling systems. The AAD says indoor heating in winter can remove moisture from the skin
Long, hot showers	The AAD says long, hot showers dry the skin. MedlinePlus lists bathing too often or too long
Harsh soap	The AAD says deodorant soaps and harsh cleaning products can remove oils and fats from the skin
Low humidity where you live	The AAD says people in dry areas, such as the Southwestern United States, often get dry skin
Wet work	The AAD says jobs that keep hands in water or harsh chemicals can remove the skin's protective layer
Tight or rough clothes	The AAD says tight clothes and wool or polyester against the skin can make dry skin worse

Showers. The AAD advises baths and showers of five to ten minutes in warm water. Pat the skin dry with a towel. The AAD says rubbing can irritate severely dry skin.

Soap. The AAD says some products, such as deodorant soaps, are too harsh for dry, sensitive skin, and recommends products labeled fragrance-free. It warns that a product labeled "unscented" can still contain chemicals that hide other smells, and these can irritate dry skin.

Air. A humidifier adds moisture to the air. The AAD suggests placing a portable one in the bedroom and running it while you sleep, and cleaning it regularly to prevent mold.

Skin care. Over-washing and scrubbing add to dryness. The AAD's moisturizer guide says people often make the mistake of exfoliating dry, peeling skin in winter, which removes more moisture. For face washing, the AAD advises a gentle cleanser twice a day and after sweating. How to treat dry skin on your face puts these steps into a routine.

How to find your own cause

Most people have more than one cause at once, such as winter air plus long hot showers plus a strong soap. Work through the list in order, starting with the causes that are easiest to change.

1. Look at your washing. How long are your showers, and how hot? Do you use a deodorant soap or a foaming wash with fragrance on your face? Switch to five to ten minute showers in warm water and a gentle, fragrance-free cleanser, as the AAD advises.
2. Look at your air. Is the heating on, or do you live somewhere dry? Try a humidifier in the bedroom at night.
3. Look at your products. Did the dryness start after a new acne treatment, toner or scrub? Before any new product, patch test it. Acne treatments dry the skin by design. Use an over-the-counter one less often, and ask your prescriber before changing a prescribed one.
4. Look at your hands and work. Frequent hand washing and wet work dry the skin fast. The AAD suggests gloves for dishes and other wet tasks, and hand cream after each wash.
5. Give it two weeks. The AAD says effective self-care usually shows improvement within 2 weeks. Keep a short record of what you changed and how your skin feels.

If none of these changes helps after two weeks, the cause is more likely to be one of the medical ones below, and a doctor is the next step.

Age and skin tone

Age. The AAD says that with age, the skin makes less sebum, the oil that keeps skin soft. By your 40s the amount drops a great deal, and it keeps dropping after 40. The AAD says that by 60 years of age, nearly everyone has dry skin. MedlinePlus adds that skin gets thinner with age. The AAD's moisturizer guide says people going through perimenopause and everyone 50 and older should use a cream moisturizer.

Skin tone. The AAD says research shows that people with brown, black or fair skin are more likely to develop severe dry skin than people with a medium complexion, such as people with Mediterranean ancestry.

Medicines and acne treatments

Some medicines list dry skin as a side effect. The AAD names statins, which lower cholesterol, and diuretics, which remove water from the body. It also says chemotherapy, targeted cancer therapy and radiation can cause severely dry skin, and that dry or thickening skin during cancer treatment should be seen by a dermatologist right away. MedlinePlus says certain medicines, both creams and pills, can cause dry skin.

Acne treatments dry the skin too. The AAD's page on moisturizer says benzoyl peroxide, salicylic acid, retinoids such as adapalene and tretinoin, and isotretinoin tend to dry and irritate the skin, and that a daily moisturizer helps skin tolerate them. Retinoid dryness and peeling explains how to manage it.

Never stop a prescribed medicine because of dry skin. Ask the doctor who prescribed it whether dry skin is a known side effect and what you can do.

Health conditions that cause dry skin

The AAD lists several conditions known to cause excessively dry skin:

• Diabetes, thyroid disease and kidney disease. The AAD says dialysis raises the risk further, because it removes water from the body.
• Skin conditions, including atopic dermatitis, ichthyosis, perioral dermatitis, psoriasis and seborrheic dermatitis. The AAD says many adults who had atopic dermatitis as children live with severely dry skin.
• Low levels of nutrients. The AAD names vitamin D, vitamin A, niacin, zinc and iron. It also lists anorexia, because the skin does not get the nutrients it needs.
• HIV. The AAD says excessively dry skin is common in people who are HIV positive, even on treatment.
• Smoking, which the AAD says speeds up skin aging so the skin becomes drier.

Only a doctor can tell whether one of these is behind your dry skin. MedlinePlus says that if a provider suspects an undiagnosed health problem, tests will likely be ordered.

When dry skin needs a doctor

The AAD says that with the right self-care, many people heal dry skin at home, and when care works you tend to see improvement within 2 weeks. It also says that if dry skin continues or gets worse, something other than dry air may be causing it.

See a doctor or dermatologist if:

• your dry skin has not improved after two weeks of gentle washing, short warm showers and moisturizer several times a day
• dryness and itching keep you from sleeping, scratching leaves open cuts or sores, or you feel itchy with no visible rash, as MedlinePlus lists
• the skin is painful, cracked, bleeding or stinging, which the AAD names as reasons to book an appointment
• you have dry skin together with other new symptoms you cannot explain

Dry, cracked or itchy skin that does not improve can also be eczema, a skin condition that needs a proper diagnosis (eczema vs dry skin sets out the signs). A doctor can tell the difference and prescribe a stronger moisturizer or medicine if needed. If your dry skin comes with pimples, can dry skin cause acne? explains how the two connect.