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Blisters
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Skin Hair Nails

Blisters

Blisters are fluid-filled sacs on the outer layer of the skin, most commonly caused by friction, heat, or underlying skin conditions.

What are blisters?

Blisters are fluid-filled sacs on the outer layer of your skin. They form because of rubbing, heat, or diseases of the skin. They are most common on your hands and feet.

Other names for blisters are vesicles (usually for smaller blisters) and bulla (for larger blisters).

What causes blisters?

Blisters often happen when there is friction—rubbing or pressure—on one spot. For example, if your shoes don't fit quite right and they keep rubbing part of your foot, or if you don't wear gloves when you rake leaves and the handle keeps rubbing against your hand. Other causes of blisters include:

  • Burns
  • Sunburn
  • Frostbite
  • Eczema
  • Allergic reactions
  • Poison ivy, oak, and sumac
  • Autoimmune diseases such as pemphigus
  • Epidermolysis bullosa, an illness that causes the skin to be fragile
  • Viral infections such as varicella zoster (which causes chickenpox and shingles) and herpes simplex (which causes cold sores)
  • Skin infections including impetigo

What are the treatments for blisters?

Blisters will usually heal on their own. The skin over the blister helps keep out infections. You can put a bandage on the blister to keep it clean. Make sure that there is no more rubbing or friction on the blister.

You should contact your health care provider if:

  • The blister looks infected—if it is draining pus, or the area around the blister is red, swollen, warm, or very painful
  • You have a fever
  • You have several blisters, especially if you cannot figure out what is causing them
  • You have health problems such as circulation problems or diabetes

Normally you don't want to drain a blister, because of the risk of infection. But if a blister is large, painful, or looks like it will pop on its own, you can drain the fluid.

Can blisters be prevented?

There are some things you can do to prevent friction blisters:

  • Make sure that your shoes fit properly
  • Always wear socks with your shoes, and make sure that the socks fit well. You may want to wear socks that are acrylic or nylon, so they keep moisture away from your feet.
  • Wear gloves or protective gear on your hands when you use any tools or sports equipment that cause friction.

Frequently Asked Questions

It is generally best not to pop a blister because the intact skin acts as a natural barrier against bacteria. If the blister is very large and painful, a healthcare provider may drain it using sterile techniques. If you must drain it yourself, wash your hands and the area, sterilize a needle with alcohol, and prick a small hole at the edge to let the fluid drain. Do not remove the overlying skin, and cover the area with a sterile, non-stick bandage to prevent infection.
Watch for signs such as the blister turning cloudy or filled with pus, increased redness spreading around the blister, warmth, swelling, or severe pain. If you develop a fever, chills, or red streaks extending from the blister, seek medical care immediately. People with diabetes or poor circulation are at higher risk for serious infections and should have any blister evaluated by a professional rather than treating it at home.
Most minor blisters heal within one to two weeks. If the top layer of skin peels off, the underlying skin will be pink and sensitive. Keep the area clean and dry, and apply a thin layer of antibiotic ointment or petroleum jelly to keep it moist. Cover it with a non-stick bandage to protect it from friction and dirt. Change the dressing daily or whenever it becomes wet or dirty.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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