A chilblain is a painful, itchy swelling that appears on your fingers, toes, ears, or nose after they've been exposed to cold, damp conditions and then warmed up too quickly. The affected skin becomes red, puffy, and extremely itchy, sometimes developing blisters.

Chilblains happen when small blood vessels under your skin react badly to sudden temperature changes. Imagine coming inside after building a snowman with bare hands and immediately holding them over a heater: that rapid warming can trigger chilblains. The swelling and itching can last for days or even weeks.

The condition was much more common a century ago, when homes were poorly heated and people spent more time in cold, damp conditions. Today, you're most likely to get chilblains if you warm cold hands or feet too quickly, like by running them under hot water or placing them directly on a radiator. The best way to warm cold fingers or toes is gradually, starting with cool or lukewarm water.

While chilblains are uncomfortable and annoying, they're usually not dangerous and heal on their own.