Definition

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

Blisters

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Causes

Causes of blisters include:

    
  • Friction or constant pressure, such as from wearing a tight-fitting shoe or gripping a tool
  • Second-degree burns, including sunburn
  • Viral infections, such as chickenpox or shingles
  • Fungal infections such as athlete’s foot
  • Contact dermatitis, such as poison ivy or oak
  • Allergic reactions, drug reactions, certain cancers, and inflammatory conditions
  • Severe skin swelling, especially of the legs

    • Risk Factors

    Factors that increase your chance of getting blisters include:

        
  • Wearing ill-fitting shoes
  • Repetitive work with hand tools
  • Getting a sunburn

    • Symptoms

    Symptoms may include:

        
  • Fluid-filled bump on the skin, which is often round
  • Fluid is usually clear, but may be bloody

    • Diagnosis

    You can diagnose a blister by its appearance and by the activity you were doing when it appeared. Seek medical attention if the blister is unusually painful, appears infected, or occurs with a burn.

    Treatment

    A blister will often heal without treatment. Some general tips for treatment include:

    Protect the Area

        
  • Be gentle with the injured area. To prevent further injury, put a bandage over the affected area. The blister should begin to shrink in about seven days.
  • Do not pop or lance the blister. Opening the blister increases the chance of infection and delays healing.
  • In the case of poison ivy or a viral infection, do not scratch the blister. If necessary, call your doctor for medicine to relieve any itching or discomfort.

    • Wash the Area

    If the blister is closed, wash the area with soap and water. Apply a bandage to protect it. If the blister is open, wash the area, apply an antibiotic ointment, and then cover it with a sterile dressing or bandage.

    See Your Doctor If:

    A blister usually heals by itself. See your doctor if:

        
  • The blister is unusually large (for example, bigger than a nickel)
  • The blister is in a critical area, such as on the face or the groin
  • The blister is associated with a burn
  • There are signs of infection, such as increasing redness around the blister, red streaks, severe swelling, pus drainage, fever, or an increase in pain

    • Prevention

    To help prevent blisters:

        
  • 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.