what causes chilblains

Chilblains are caused by an abnormal reaction of the small blood vessels in your skin to cold, damp conditions, especially when the skin is rewarmed too quickly.

What causes chilblains?

When your skin is exposed to chilly, damp weather, the tiny blood vessels near the surface constrict (narrow) to conserve heat. If the area is then warmed too fast (for example, putting cold hands or feet directly next to a heater), the vessels suddenly widen, and they cannot handle the quick rush of blood. Fluid and blood leak into nearby tissues, leading to red or purple swollen patches that burn or itch – these are chilblains.

On a microscopic level, prolonged cold exposure slows circulation and can cause partial blockage of the capillary bed, contributing to inflammation of the skin (pernio). That’s why chilblains often appear 12–24 hours after being out in cold, damp conditions instead of immediately.

Main triggers and risk factors

You are more likely to get chilblains if your circulation or skin reacts strongly to cold.

Key triggers and risk factors include:

• Exposure to cold, damp, or windy weather, especially when temperatures are cold but not freezing.

• Rapid rewarming of cold skin, such as putting icy toes directly in hot water or near a strong heat source.

• Poor circulation or vascular conditions (for example, Raynaud’s phenomenon or peripheral arterial disease).

• Low body weight or low body mass index (BMI), which gives less natural insulation against the cold.

• Smoking, because nicotine makes blood vessels constrict even more.

• Wearing tight shoes or clothing that both restricts blood flow and exposes parts of the skin to the cold.

• Living in cold, humid climates and homes that are not evenly heated (localized heat sources).

• Being a child, teenager, or young to middle‑aged woman, possibly related to body size, hormones, and clothing choices.

• Inactivity during cold weather, since less muscle movement means slower circulation to hands and feet.

Underlying health conditions

Sometimes chilblains are “primary” (no other disease behind them), but they can also be “secondary” to other conditions.

Conditions that can be associated with chilblains include:

• Connective tissue diseases, especially systemic lupus erythematosus (SLE) and forms of chilblain lupus.

• Raynaud’s phenomenon, where cold triggers excessive narrowing of the small blood vessels in fingers and toes.

• Peripheral arterial disease (reduced blood flow to the legs).

• Autoimmune or blood disorders (for example, some bone marrow or plasma cell diseases).

• Conditions causing poor nutrition or very low BMI, such as anorexia nervosa or untreated celiac disease.

• In some reports, infections such as COVID‑19 have been linked to chilblain‑like lesions in certain people.

If chilblains are frequent, severe, or appear in unusual places, doctors may look for these underlying issues.

Why some people get them and others don’t

Not everyone exposed to cold, damp weather will develop chilblains. Differences in how strongly a person’s blood vessels constrict, how quickly they rewarm, and their overall circulation and body composition all play a role. Genetics and immune factors may also contribute, especially in chilblain lupus and familial forms linked to specific gene mutations affecting immune signaling.

In everyday terms, chilblains happen where cold plus dampness plus vulnerable blood vessels meet. Two people can stand side by side in the same winter weather; the one who smokes, has low body weight, or has an underlying vascular or autoimmune condition is more likely to walk away with painful, itchy red patches on the fingers or toes.

Simple illustration

Imagine your skin’s tiny blood vessels as flexible pipes. In the cold, the pipes tighten to conserve warmth. If they are suddenly blasted with hot water, the valves fly open too quickly. Some fluid spills into the surrounding “walls,” causing swelling, redness, and irritation — that “spill” is essentially what you see as chilblains on the skin.

Information gathered from public forums or data available on the internet and portrayed here.