A blister is a fluid-filled bump on the skin.


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Blisters have many causes, such as:

  • Friction or constant pressure
  • Second-degree burns
  • Infections
  • Skin irritation from:
  • Certain cancers
  • Blistering diseases—such as epidermolysis bullosa, porphyria, or pemphigus
  • Autoimmune disorders

Risk Factors

Things that may increase the risk of blisters are:

  • Wearing ill-fitting shoes
  • Repetitive work with hand tools
  • Getting a sunburn or frostbite
  • Severe skin swelling, especially of the legs


Symptoms of a blister are:

  • A fluid-filled bump on the skin, which is often round
  • Fluid that is usually clear, but may be bloody, cloudy, or contain pus


The doctor will ask about your symptoms and health history. A physical exam will be done. Blisters may be diagnosed on appearance.


A blister will often heal without treatment. Sometimes the underlying cause needs to be treated.

Treatment options are:

  • Washing the area
  • Applying over-the-counter medicine—to ease itching and discomfort
  • Applying antibiotic ointment—to prevent or treat an infection
  • Bandaging the area—to protect it


To lower the risk of a blister:

  • Wear shoes that fit properly. Always wear socks with your shoes.
  • Use gloves or protective padding when working with tools.
  • Wear a hat, protective clothing, and sunscreen when out in the sun.
  • Avoid skin contact with irritating chemicals or plants


American Academy of Dermatology
National Institute of Arthritis and Musculoskeletal and Skin Diseases


Canadian Dermatology Association


Abiad M, Kurban M, Abbas O. Recurrent blisters with pain following thermal burn injury to left leg and foot. Int J Dermatol. 2019;58(12):1377-1378.
Blistering skin conditions. DermNet New Zealand website. Available at: Accessed January 29, 2021.
Blisters. Better Health Channel website. Available at: Accessed January 29, 2021.
Blisters—causes. NHS Choices website. Available at:
...(Click grey area to select URL)
Accessed January 29, 2021.
Blisters, calluses, and corns. Kids Health—Nemours Foundation website. Available at:
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Accessed January 29, 2021.
Major burns. EBSCO DynaMed website. Available at: Accessed on February 18, 2021.
Last reviewed September 2020 by EBSCO Medical Review Board Shawna Grubb, RN