Chilblains

Small red or purple patches on the toes, usually appearing a day or so after your feet have been cold. Intensely itchy indoors, burning or sore rather than itchy once they are established. Sometimes swollen, occasionally blistering.

They turn up reliably through a Melbourne winter, and almost always in houses that are cold rather than in genuinely freezing conditions.

What is actually happening

Chilblains are an abnormal reaction of the small blood vessels near the skin surface to cold, followed by rewarming.

When the foot gets cold, those vessels constrict. When it warms up again, they dilate — and in people prone to chilblains that dilation happens faster than the surrounding tissue can accommodate, so fluid leaks into the skin and an inflammatory reaction follows. The lesion appears some hours later.

Which makes the trigger the rewarming rather than the cold itself. This is the single most useful thing to understand about them, because the instinctive response to cold feet — the heater, the hot water bottle, the hot shower — is precisely the thing that sets them off.

What makes some people prone to them

• Naturally poor peripheral circulation, and being cold-handed and cold-footed generally
• Being lean, with less insulating tissue
• Smoking, which constricts peripheral vessels
• Damp as much as cold, which is why wet socks matter
• Raynaud’s phenomenon and some connective tissue disorders
• Certain medications that affect circulation
• A family history, which is common

What helps

Prevention through the season does more than treating each one.

• Keep feet consistently warm rather than cycling between cold and hot. Wool or thermal socks, indoors as well as out, and warm slippers on cold floors.
• Warm cold feet gradually, at room temperature. Not a heater, not a hot water bottle, not a hot shower.
• Keep them dry. Change out of damp socks promptly.
• Do not sit with feet against a heater. It is the most common trigger there is.
• Keep moving through the day to maintain circulation.
• If you smoke, this is one of the many things it makes worse.

For an established chilblain: protect it, resist scratching, and let it settle. Your podiatrist can dress a broken one, offload a lesion that is being rubbed by footwear, and advise on padding where a toe deformity means a chilblain keeps forming at the same pressure point.

When to have them looked at

⚠ If you have diabetes or known circulation problems, do not manage these at home. A broken chilblain is an open wound on a foot with a reduced ability to heal it, and the sensation loss that often accompanies diabetes means you may not feel it worsening. Book a diabetic foot assessment.

Worth an appointment for anyone:

• A chilblain that has broken down or ulcerated
• Signs of infection — spreading redness, warmth, discharge, increasing pain
• Lesions on one foot only, which raises the question of a local circulatory cause
• Chilblain-like lesions appearing outside cold weather, which warrants medical investigation rather than podiatric management alone
• Recurrent severe seasons despite doing all of the above