BLISTERS - Watsons Health


Blisters are small pockets of fluid that usually form in the upper layers of skin after it has been damaged, cushioning the tissue underneath. This protects the tissue from further damage and allows it to heal.

Blisters can develop anywhere on the body but are most common on the hands and feet. Most blisters are filled with a clear fluid (serum), but may be filled with blood (blood blisters) or pus if they become inflamed or infected.

Blisters are most often caused by skin being damaged by friction or heat.

A friction blister can develop if the skin is rubbed for a long period or if there’s intense rubbing over shorter periods. Friction blisters often occur on the feet and hands, which can rub against shoes and handheld equipment, such as tools or sports equipment. Blisters also form more easily on moist skin and are more likely to occur in warm conditions. Friction blisters are common in people who are very active, such as sports players and those in the military. They’re usually caused by poor-fitting shoes.

Blisters can also develop when skin is exposed to excessive heat – for example, when you have sunburn.

Blisters can sometimes form when your skin comes into contact with substances such as cosmetics, detergents and solvents.

They can also develop as an allergic reaction to an insect bite or sting.

A number of medical conditions may cause blisters. The most common are:

  • Chickenpox – a childhood illness that causes itchy red spots
  • Cold sores – small blisters that develop on the lips or around the mouth, caused by a virus
  • Herpes – a sexually transmitted infection (STI) that most commonly affects the groin
  • Impetigo – a contagious bacterial skin infection
  • Pompholyx – a type of eczema
  • Scabies – a skin condition, caused by tiny mites, which may lead to blisters developing on young children’s feet or palms of their hands
  • Hand, foot and mouth disease – a viral infection that usually affects young children


If the cause of your blisters is not obvious, your doctor will ask about your family history and your personal medical history, including any allergies you have and any medications you take, including over-the-counter medications. You also will be asked about any recent exposure to irritating chemicals or allergens.

Your doctor often can diagnose the cause of your blisters by their appearance and your history. If your doctor suspects an allergic reaction, he or she may recommend patch tests with chemicals to identify the allergen. Some blistering diseases are diagnosed with a skin biopsy, in which a small piece of tissue is removed and examined in a laboratory.



Usually, it is best to leave blisters alone. Because blisters protect the underlying skin, breaking blisters open can increase the chance of infection. Protect blisters with a bandage and cover them until they heal on their own. The liquid in the blister will be re-absorbed and the skin will flatten naturally. If a blister breaks, wash the area with soap and water, then apply a bandage. If a blister is very large or painful, your doctor may drain it and apply an antibacterial cream to prevent infection.

The treatment for blisters caused by eczema, infections and other diseases varies. Some cases of eczema can be treated with corticosteroid cream or pills. Herpes simplex infections and shingles (herpes zoster) sometimes are treated with antiviral medications. Antibiotic cream or pills may be given for impetigo. Chickenpox and coxsackievirus generally are left to go away on their own. The itching caused by chickenpox can be relieved with over-the-counter anti-itch lotions, such as calamine. With medication-related erythema multiforme, the medication must be discontinued immediately. Corticosteroids sometimes may be prescribed.

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