What causes dry skin, and when it needs a doctor

Dry skin is not a single cause but the result of a breakdown in the skin barrier's ability to hold on to moisture. Sometimes the cause is a simple daily habit like a hot shower, and sometimes it is a signal of an internal condition that deserves attention. Understanding exactly what causes dry skin is the first step to treating dry skin, because what fixes passing winter dryness is very different from what skin affected by eczema needs. This guide breaks the causes down from mildest to most serious, and shows when dryness is a sign to see a doctor.

Healthy skin has an outer layer of cells and lipids that works like a wall, stopping water from evaporating. When that wall weakens, water leaks out and irritants get in, so roughness, tightness and itching appear.

Causes of dry skin: external versus internal

The causes of dry skin fall into two broad groups worth telling apart. The external group covers everything that touches the skin each day — hot water, cleansers and weather — and is behind most mild, passing cases of dry skin. The internal group covers hormonal changes, ageing and certain medical conditions, and is often behind severe, persistent dryness.

This split is practical because it points you towards the right solution: external factors are managed by adjusting habits and moisturising, while internal ones may need a medical diagnosis. Knowing which group is behind your dryness saves you from testing remedies that never touch the real cause, so the sections below cover the main causes of dry skin in more detail.

How the skin loses its moisture

The fundamental cause of dry skin is water loss through a damaged barrier. The outer skin layer is built like a brick wall: the cells are the bricks, and the natural lipids (ceramides, cholesterol and fatty acids) are the mortar that binds them and traps moisture. Anything that dissolves that mortar or cracks the wall lets water escape.

The most common everyday factors include:

Hot water and long showers, which dissolve the protective oils.
Alkaline soaps and harsh cleansers, which strip the skin of its lipids.
Over-exfoliating, which weakens the barrier instead of renewing it.
Air conditioning and heating, which lower the humidity of the surrounding air.
Ageing, which gradually reduces the production of sebum and natural lipids.

Rough skin and changes in texture

When dryness continues, smooth skin turns rough and flaky. Rough skin is linked to a build-up of dead cells on the surface that do not shed normally because there is not enough moisture, leaving the skin looking dull and uneven. Friction from woollen clothing, exposure to wind, and the chemicals in some household cleaning products add to the roughness too.

An important distinction: mild, temporary roughness improves with moisturising, but thick, persistent roughness in specific areas (elbows, knees) can point to a skin condition that needs assessing.

Why dry skin gets worse in winter

Dry skin in winter is almost universal, and it comes from several factors stacking up together. Cold air carries less moisture, indoor heating dries the air further, and people tend to shower in hotter water. The result is that the rate of water loss through the skin rises noticeably in the colder months.

Seasonal factor	Effect on skin	Suggested adjustment
Lower air humidity	Faster water loss from the surface	Indoor humidifier plus a richer cream
Central heating	Constant drying of the surrounding air	Reapply moisturiser through the day
Long, hot showers	Dissolving of protective lipids	Lukewarm water, shorter time
Cold, dry wind	Surface cracking and roughness	A protective, occlusive layer before going out

The simple winter rule: swap lightweight, water-based moisturisers for richer formulas with occlusive ingredients that lock in moisture, and apply them to damp skin straight after showering.

What causes severe dry skin

Passing dryness is different from severe, persistent dry skin that does not respond to ordinary moisturising. Severe dryness often means the skin barrier is deeply damaged, or that an internal factor is depriving the skin of its lipids and moisture. Signs of severe dryness include cracking that may bleed, itching that disturbs sleep, and widespread redness that does not settle.

This type is not solved by changing a cream; it calls for finding the root cause, and sometimes a prescribed treatment to repair the barrier or calm inflammation under medical supervision. It also helps to know how strong actives like tretinoin affect the skin, since they can add to dryness if used without enough moisture.

Gauging how severe your dryness is

This map helps you judge whether your dryness can be managed at home or needs assessing. It reads left to right:

flowchart TD
  A[Dry, rough skin] --> B{Intense itching or bleeding cracks?}
  B -->|Yes| C[Possibly severe dryness]
  B -->|No| D[Mild to moderate dryness]
  D --> E[Adjust habits plus regular moisturising]
  E --> F{Improved within two weeks?}
  F -->|Yes| G[Continue the protective routine]
  F -->|No| C
  C --> H[See the clinic to rule out an internal cause]

Medical conditions that cause dry skin

In some cases dryness is not superficial but a symptom of something deeper. The conditions associated with dry skin include both skin disorders and internal ones — some of which bring on dryness across the skin and hair together — which is why unexplained, persistent dryness should not be ignored.

Condition	How it links to dryness	Signals that may appear
Eczema (atopic dermatitis)	An inherited weakness in the skin barrier	Intense itching, redness, recurring patches
Psoriasis	Accelerated cell turnover and build-up	Thick, silvery scale on defined plaques
Underactive thyroid	Slowed metabolism and sebum production	Fatigue, feeling cold, changes in weight and hair
Diabetes	Effects on circulation and hydration	Thirst, persistent dryness especially on the limbs

This list is for awareness, not self-diagnosis. Having dry skin does not necessarily mean a disease, but severe, persistent dryness alongside general symptoms deserves a medical check. Cases vary from person to person, and an accurate diagnosis needs a doctor.

Protecting a dry skin barrier day to day

Because most everyday dryness comes down to a weakened barrier, the practical fix is to stop stripping it and start supporting it. A few consistent habits do more than any single "miracle" product:

Shorten and cool down washing. Lukewarm water and briefer showers spare the protective lipids that hot water dissolves.
Choose a gentle, non-foaming cleanser. Harsh, high-lather soaps leave skin feeling squeaky and tight — a sign the barrier has just been stripped.
Moisturise on damp skin. Applying a moisturiser within a couple of minutes of washing traps the water still sitting on the surface, rather than letting it evaporate.
Layer for the weather. In dry or cold conditions, a richer, occlusive layer over a humectant holds moisture in far better than a light lotion alone.
Ease off exfoliation. Scrubs and strong acids used too often thin the barrier; on already-dry skin, less is genuinely more.

The pattern behind all of these is the same: reduce what removes moisture, and reinforce what keeps it in. For passing, weather-driven dryness this is usually enough on its own, and it is also the sensible baseline even when an underlying condition is involved. What it cannot do is override a genuine internal cause — which is exactly why dryness that ignores a careful routine is worth having assessed rather than simply met with a stronger cream.

Frequently asked questions

What is the most common cause of dry skin?

The most common cause is damage to the skin barrier from everyday external factors: hot water, harsh soap, dry air, and over-cleansing or over-exfoliating. These strip the natural lipids that trap moisture in the skin, so water is lost and the skin turns rough and tight. Adjusting these habits alone improves most mild cases.

When is dry skin a sign of a medical condition?

Persistent, severe dryness can point to conditions such as eczema, psoriasis, an underactive thyroid or diabetes, especially alongside intense itching, cracking, or changes in weight and energy. If dryness does not improve despite regular moisturising for several weeks, or comes with other physical symptoms, a medical assessment is important to rule out an internal cause.

Why does dry skin get worse in winter?

In winter the outdoor air holds less moisture, while indoor heating dries the air further, so water evaporates quickly from the skin surface. Very hot showers in cold weather also dissolve the skin's protective lipids. The result is roughness and cracking that worsen in the colder months and call for a richer, more frequent moisturiser.

Does not drinking enough water cause dry skin?

Drinking water matters for general health, but dry skin is rarely caused by low water intake alone. Visible dryness is mostly about the state of the outer skin barrier and its ability to hold moisture, not internal fluid levels. That is why the right topical moisturiser matters more than simply drinking more water for surface dryness.

When to visit the clinic

Most dry skin improves with adjusted habits and regular moisturising over a few weeks. But if the dryness is severe or widespread, comes with itching that disturbs sleep or cracking that bleeds, has not responded to home care after several weeks, or is accompanied by other physical symptoms such as fatigue or weight change, it is wise not to rely on creams alone. At InJasmine we begin by assessing the state of your skin barrier and looking for any possible internal cause before setting a moisturising or treatment plan suited to your case.