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.
Most blisters are filled with a clear fluid (serum). This cushions the tissue underneath. It protects the tissue from further damage and allows it to heal.
Blisters may be filled with blood (blood blisters) or pus if they become inflamed or infected.
Blisters can be caused by:
Friction blisters are common in people who are very active like sports players and those in the military. They’re usually caused by poor-fitting shoes.
A blister can develop if the skin is rubbed for a long period or if there’s intense rubbing over shorter periods.
Friction blisters often occur on the feet and hands. These can rub against shoes and handheld equipment like tools or sports equipment. Blisters also form more easily on moist skin and are more likely to occur in warm conditions.
Blisters can appear when skin is exposed to excessive heat – for example, when you have sunburn.
Blisters can sometimes form when your skin comes into contact with cosmetics, detergents and solvents.
They can also develop as an allergic reaction to an insect bite or sting.
Some medical conditions may cause blisters. The most common are:
Several rarer conditions can also cause blisters. They are:
Most blisters heal naturally after 3 to 7 days and don’t need medical attention.
It’s important to avoid bursting the blister. This could lead to an infection or slow down the healing process.
As new skin grows underneath the blister, your body slowly reabsorbs the fluid in the blister. The skin on top will dry and peel off.
If the blister does burst, don’t peel off the dead skin. Instead, allow the fluid inside the blister to drain and cover the area with a dry, sterile dressing. This will protect it from infection until it heals.
You have blisters that:
Antibiotics may be prescribed to treat an infected blister.
If you have a large or painful blister, your GP may decide to decompress the blister under sterile conditions.
If your blisters are caused by a medical condition, your GP will be able to tell you how to treat the underlying condition.
The unbroken skin over a blister provides a natural barrier to infection. It’s important that the skin remains intact to avoid infection.
As tempting as it may be, try not to pierce a blister with a needle. This could lead to an infection or slow down the healing process. Allow the skin to peel off on its own after the skin beneath has healed.
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.
Painful blisters, or those in positions where they’re likely to burst, such as on the sole of your foot, can be covered with a soft dressing to cushion and protect them. It may help to cut the dressing into a ‘doughnut’ shape to fit around the blister and avoid placing pressure directly on it.
Change the dressing daily and wash your hands before touching the blister to avoid infection.
If a blister has burst, don’t peel off the dead skin on top of the blister. Allow the fluid inside to drain and wash it with mild soap and water. Cover the blister and the area around it with a dry, sterile dressing to protect it from infection until it heals.
Hydrocolloid dressings have been shown to help prevent discomfort and encourage healing. These are available over the counter from pharmacies,
If the top layer of dead skin from a burst blister has already rubbed off, don’t pick at the edges of the remaining skin. Follow the advice above to protect it from infection.
If the blister is on your foot, avoid wearing the shoes that caused it, at least until it heals.
Blood blisters should be left to heal naturally. If a blood blister bursts, keep the area clean and dry. Protect it with a sterile dressing to prevent infection.
Blood blisters are often painful. Applying an ice pack to the affected area immediately after the injury can help relieve the pain (a bag of frozen vegetables works just as well). Between 10 and 30 minutes should help.
To stop the ice touching your skin directly, place a towel over the affected area before applying the ice pack.
There are a number of things you can do to avoid getting blisters caused by friction, sunburn or chemicals.
Blisters caused by a medical condition often can’t be prevented and need to be treated by a GP.
Last updated:
14 November 2023