Understanding Blisters -- the Basics

What Are Blisters?

Most blisters happen from irritation or other damage to the skin from something outside the body, such as a shoe. Some diseases can cause blisters, fluid-filled lesions between the two top, superficial, layers of the skin.

A single blister is usually from friction or a burn, typically on the hands or feet.

Blisters all over the body may be a sign of a serious, life-threatening disease; call your doctor.

What Causes Blisters?

Blisters are caused by several things:

Friction: Blisters can happen when something rubs against skin, such as a tool handle against the hand or a new pair of shoes against the ankle. Unlike corns and calluses, which develop from prolonged rubbing, friction blisters come from brief, intense rubbing on a small area.

Burns: Flames, steam, or touching a hot surface can cause blisters, as can severe sunburn or radiation.

Cold: Extreme cold can cause blisters. For example, when a wart is frozen off, a blister will grow.

Contact with irritants or allergens: Skin may blister when it comes in contact with some chemicals, cosmetics, and many plant allergens. This is called irritant or allergic contact dermatitis.

Drug reactions: Many people develop blisters as a reaction to taking certain drugs. Before prescribing any new drugs, your doctor should ask about any drug reactions you have had in the past. If you develop a blister while on medication, call your doctor.

Autoimmune diseases: Three diseases of the immune system commonly cause blisters:

  • Pemphigus vulgaris, a potentially fatal skin disease, causes blisters in the mouth or skin; these painful blisters become raw and crusted after bursting.
  • Bullous pemphigoid causes less severe blisters that heal faster and are not life-threatening; this condition is seen mostly in elderly people.
  • Dermatitis herpetiformis causes small, itchy blisters; it is a chronic condition that usually starts in early adulthood. It is associated with gluten sensitivity.

Infection: Blisters are a common symptom of many infectious illnesses, including chickenpox, cold sores, shingles, and a skin infection called impetigo.

Genes: There are rare genetic diseases that cause the skin to be fragile and to blister.

WebMD Medical Reference Reviewed by Sabrina Felson, MD on March 16, 2017


American Academy of Family Physicians.


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