What Causes Blisters?

Reviewed on 9/10/2021

Blisters are fluid-filled bumps on the skin typically caused by friction, burns, allergic skin reactions, immune system problems, and medical conditions (chickenpox, herpes, scabies, and others).
Blisters are fluid-filled bumps on the skin typically caused by friction, burns, allergic skin reactions, immune system problems, and medical conditions (chickenpox, herpes, scabies, and others).

Blisters are small fluid-filled bumps that form on the upper layers of skin. The fluid accumulates under damaged skin to cushion the underlying tissue, protecting it so it can heal. Blisters commonly develop on the feet and hands, but can occur anywhere on the body. 

Causes of blisters include:

  • Friction
    • Something rubs or presses against the skin
    • Commonly occurs from poor-fitting shoes or in people who play sports and use handheld equipment 
    • Friction blisters form more easily on moist skin and in warm conditions
  • Burns, including sunburn
  • Skin reactions
  • Problems with the body's immune system
  • Certain medical conditions

What Are Symptoms of Blisters?

Blisters are fluid-filled bumps on the skin. Fluid is usually clear (serum) but may be filled with pus if infected. Blood blisters are filled with blood. 

When to See the Doctor for Blisters

See a doctor if you have blisters that: 

  • Are filled with pus
  • Are in the mouth, near the eyes, or in or near the anus or genitals
  • Are all over the body
  • Are painful
  • Keep coming back
  • Appear after severe sunburn, burns or scalds, or an allergic reaction
  • Develop after coming into contact with chemicals or other substances

How Are Blisters Diagnosed?

Blisters are usually diagnosed with a skin examination. Tests such as a skin biopsy may be indicated to help determine the cause of the blisters if it is unknown. 

What Is the Treatment for Blisters?

Blisters often heal on their own without treatment in about a week. 

First aid care at home to treat blisters includes:

  • Clean the area with soap and water
  • Cover small blisters with a bandage 
  • Cover larger blisters with a gauze pad that is taped in place
  • Cover blisters that are painful or in areas prone to bursting (such as the foot) with a soft bandage and cushion to protect them
  • Change the bandage daily
  • If a blister pops:
  • Keep the area clean 
  • Don’t peel off the dead skin on top of the blister
  • Cover with a bandage to protect it
  • Do not: 
  • Wear shoes that cause a blister on the foot until the blister heals
  • Pop or poke a blister unless instructed to do so by a healthcare professional, because this can result in infection and slower healing
  • Scratch blisters, which also makes them more prone to infection
  • If blisters itch, medicines may be recommended to help relieve itching

Medical treatment for blisters includes: 

  • Antibiotics, if a blister becomes infected
  • Decompression of the blister by a medical professional
  • Treating any underlying condition that is causing the blisters

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Reviewed on 9/10/2021
References
https://www.uptodate.com/contents/blisters-the-basics?search=blisters&source=search_result&selectedTitle=1~150&usage_type=default&display_rank=1

https://www.nhsinform.scot/illnesses-and-conditions/injuries/skin-injuries/blisters