Blisters are small pockets of fluid that usually form in the upper layers of skin after it's been damaged. Blisters can develop anywhere on the body but are most common on the hands and feet.

Symptoms of blisters 

Most blisters are filled with a clear fluid (serum), but may be filled with blood (blood blisters) or pus if they become inflamed or infected.

Blister on a left thumb
Blisters are small pockets of clear fluid under a layer of skin
Blood blister on finger tip
Blood blisters are red or black and filled with blood instead of clear fluid

Blister on a man’s leg showing inflammation
Inflammation shows as redness around a blister

Blisters can be caused by:

Treating blisters 

Most blisters heal naturally after three to seven days and don't require medical attention.

As new skin grows underneath the blister, your body slowly reabsorbs the fluid in the blister and the skin on top will dry and peel off.

It's important to avoid bursting the blister, because this could lead to an infection or slow down the healing process.

You may choose to cover small blisters with a plaster. Larger blisters can be covered with a gauze pad or dressing that can be taped in place.

When to seek medical help 

You should see your doctor if you have blisters that:

  • you think are infected – an infected blister will be filled with yellow or green pus and may be painful, red and hot
  • are very painful
  • keep coming back
  • are in unusual places, such as on your eyelids or inside your mouth
  • are caused by severe sunburn, burns or scalds or an allergic reaction

Preventing blisters 

There are a number of ways to avoid getting blisters caused by friction, sunburn or chemicals. These include:

  • wearing comfortable, well-fitting shoes
  • helping keep your feet dry, for example, with thicker socks
  • wearing gloves when handling chemicals
  • using sunscreen

Blisters caused by a medical condition often can't be prevented and need to be treated by a doctor.

The information on this page has been adapted from original content from the NHS website.

For further information see terms and conditions.

This page was reviewed April 2018

This page is due for review April 2021

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