What are blisters?

A blister, also known as a vesicle, is a pocket of fluid that forms in the upper layers of the skin. They can be caused by infection, chemical burns, friction, freezing or burning.

Although blisters are irritating or painful, they are not typically serious and can generally heal without professional medical treatment.

Causes of blisters

Blisters commonly form when friction rubs against your skin in a particular spot for an extended period. Blisters commonly form on the hands and feet. Other causes of blistering include:

  • Contact dermatitis
    If you are allergic to latex, adhesives or poison ivy, you could develop red, inflamed skin and blisters.
  • Burns
    Severe burns, from sunburn, heat or chemicals, can cause the affected area to blister.
  • Allergic eczema
    If you have allergic eczema, you may develop blistering in the affected area.
  • Frostbite
    People who have been exposed to extreme cold weather for an extended period may develop blisters on the exposed area.
  • Impetigo
    Impetigo is a bacterial skin infection that causes blisters.
  • Herpes virus
    The herpes virus can cause chickenpox, shingles, stomatitis, cold sores or genital herpes. All these conditions can cause skin blistering.
  • Erysipelas
    Erysipelas is a blistering skin infection caused by the Streptococcus group of bacteria.
  • Skin conditions
    Skin conditions such as porphyrias, pemphigus, dermatitis herpetiformis or epidermolysis bullosa can cause your skin to blister.

Risk factors for blisters

Risk factors for developing a blister are different based upon what has caused the blister.

Risk factors for blisters on the feet include:

  • Wearing wet or poorly fitting socks or footwear
  • Living or visiting a warm, humid or damp environment
  • Wearing footwear that has not been broken in
  • Participating in long-distance walking or running

Symptoms of blisters

Symptoms of a blister include:

  • Bubble of skin filled with clear fluid that ranges in size from very small to more than an inch in diameter
  • Pain
  • Redness
  • Swelling
  • Itching

Diagnosis of blisters

You can often self-diagnose a blister at home by examining the appearance of the area. If you suspect the blister is caused by an infection or more serious skin condition, you should visit your Mercy Health doctor. Your doctor will closely examine the affected area and if necessary, take a blood test or skin sample to determine what bacteria is causing your symptoms.

Treatments for blisters

Most blisters do not need professional medical treatment. You can self-treat them by covering it with a bandage, leaving them alone and avoiding the trigger. The built-up fluids in the blister will eventually seep into the tissue, and the blister will heal. Do not puncture a blister unless it is very painful — the outer layer of skin protects the area from infection.

If you suspect your blisters are caused by an infection, schedule an appointment with your Mercy Health doctor. Your doctor will likely give you an antibiotic to treat the infection and steroid cream to relieve skin rashes. Depending on the cause of your blisters, you may need other medications to manage your symptoms.

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