Dry skin happens when your skin’s outermost layer loses moisture faster than it can replace it. The causes range from everyday habits like hot showers and harsh soaps to underlying medical conditions, genetics, and nutritional gaps. Understanding what’s behind your dry skin is the first step toward fixing it.
How Your Skin Holds Onto Water
Your skin’s outer layer, called the stratum corneum, works like a brick wall. The “bricks” are flattened skin cells, and the “mortar” is a mix of fats: ceramides (about 50%), free fatty acids (20%), and cholesterol and its esters (about 25%). Together, these lipids form thin sheets that trap water between cells and prevent it from evaporating. When researchers stripped these fats from skin using solvents, the skin became rough and scaly. Of all the individual lipids tested, ceramides were the single most effective at restoring hydration.
Your skin also produces what’s known as natural moisturizing factor, a collection of small molecules (mostly amino acids) inside skin cells. These molecules don’t hold water the same way lipids do. Instead, they help keep skin flexible and maintain the slightly acidic pH that protects against bacteria. Anything that depletes either the lipid barrier or these moisturizing molecules sets the stage for dryness.
Environmental and Seasonal Triggers
Low humidity is one of the most common causes of dry skin. When the air around you is dry, water escapes from your skin more quickly, a process called transepidermal water loss. Higher elevations make this worse because the air holds less moisture to begin with.
Winter creates a double problem. Cold outdoor air carries very little moisture, and indoor heating systems, especially forced-air furnaces, strip even more humidity from the air inside your home. You end up moving between two drying environments all day long, and your skin barrier takes the hit. This is why many people only experience dry skin from November through March, even if their skin is fine the rest of the year.
Hot Water and Harsh Cleansers
Long, hot showers feel great but work against your skin. Dermatologists at Cleveland Clinic recommend keeping shower water around 100°F (lukewarm to warm) and limiting time in the water. Anything hotter can dissolve the protective lipids in your outer skin layer, leaving it vulnerable to moisture loss.
Soaps and body washes containing strong surfactants do similar damage. Sodium lauryl sulfate, one of the most common cleansing agents, distorts cell membrane proteins and strips lipids directly from the skin’s surface. It also disrupts the community of beneficial bacteria living on your skin, some of which help maintain the acidic environment that keeps your barrier intact. Switching to a gentle, fragrance-free cleanser can make a noticeable difference within days.
Aging and Hormonal Changes
Your skin produces less of its natural oils as you get older, but the timeline differs between men and women. In men, sebum (the oily substance your skin secretes) stays relatively stable even into the 80s. In women, sebum production begins declining with menopause, which is why many women notice a sharp increase in skin dryness in their late 40s or 50s. Data from a large Chinese cohort found sebum levels peaked around age 40 in women and age 50 in men before declining.
Wax esters, another component of skin oil, peak between ages 15 and 35 and decline steadily afterward. Squalene, an unsaturated fat that helps keep skin supple, reaches its highest levels between 20 and 40 in men and drops off in the decades that follow. These gradual losses mean older skin has a thinner, less effective lipid barrier and needs more external support to stay hydrated.
Genetics and Skin Barrier Defects
Some people are genetically predisposed to dry skin. The most well-studied example involves a protein called filaggrin, produced by the FLG gene. Filaggrin does two critical jobs: it bundles structural proteins together to create a strong, flat barrier in the outermost skin cells, and when it breaks down, its fragments become key components of your skin’s natural moisturizing factor.
About 40 known mutations in the FLG gene produce an abnormally short version of the protein that can’t function properly. People with these mutations have a weakened skin barrier that lets excess water escape, resulting in chronically dry skin. These same mutations are strongly linked to atopic dermatitis (eczema) and ichthyosis vulgaris, a condition that causes persistent dry, scaly patches. If dry skin runs in your family, filaggrin mutations may be part of the explanation.
Medical Conditions That Cause Dry Skin
Persistent dry skin that doesn’t improve with moisturizer and lifestyle changes can sometimes signal an underlying health issue. Diabetes and chronic kidney disease both affect how your body manages fluids and can lead to widespread skin dryness. Eczema, contact dermatitis, and seborrheic dermatitis are skin conditions where dryness is a primary symptom. Even athlete’s foot, a fungal infection, can mimic dry skin on the feet.
Seborrheic dermatitis deserves a specific mention because it often gets mistaken for simple dryness. It causes flaky patches on the scalp (dandruff), face, chest, and skin folds. The flaking looks like dry skin but is actually driven by inflammation, which means plain moisturizer won’t resolve it.
Medications That Dry Your Skin
Certain medications reduce your skin’s oil content as a side effect. Statins, prescribed to lower cholesterol, also affect the lipids in your skin. Since your skin barrier depends on those lipids to retain moisture, people taking statins sometimes notice increased dryness. Common statins include atorvastatin, simvastatin, and rosuvastatin.
Isotretinoin, a powerful acne medication, is one of the most notorious skin-drying drugs. It works by dramatically shrinking oil glands, which clears acne but often leaves skin and lips extremely dry. If your skin became noticeably drier after starting a new medication, that connection is worth discussing with your prescriber.
Nutritional Deficiencies
What you eat affects your skin barrier from the inside. Vitamin A deficiency causes a condition sometimes called “toad skin,” characterized by dry, rough bumps with hard plugs projecting from hair follicles. These bumps typically appear symmetrically on the face, shoulders, buttocks, and the outer surfaces of arms and legs. In severe cases, they can spread across the entire body.
Vitamin B6 deficiency can cause generalized skin dryness along with a painful, inflamed tongue and red erosions in areas where skin folds touch. These nutritional causes are more common in people with limited diets, absorption disorders, or chronic illness. In well-nourished populations, they’re rare, but if your dry skin comes with other unusual symptoms like changes to your tongue, nails, or vision, a nutritional workup may be worthwhile.