Definition

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

Blisters

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Causes

Blisters have many causes, such as:

• Friction or constant pressure
• Second-degree burns
• Infections
• Skin irritation from:
  • Contact dermatitis, such as poison ivy, oak, or sumac
  • Insect bites
  • Allergic reactions
  • Reactions to certain medicines or chemicals
  • Scabies
• 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

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

Diagnosis

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

Treatment

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

Prevention

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