Skin Problems & Treatments Health Center

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 illnesses can make blisters.

 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.