What is a blister?

A blister is a bump on the skin that contains fluid. Blisters are often round or oval in shape. The fluid that forms underneath the skin can be bloody or clear.

What causes a blister?

Blisters are often caused by injury, allergic reactions, or infections, which may include:

• Burns and scalds

• Sunburns

• Friction (such as from a shoe)

• Contact dermatitis

• Impetigo, a contagious skin infection

• Viral infections, including chickenpox and herpes zoster

• Fungus

• Thumb-sucking

• Medicine reactions

Many of these symptoms may be caused by other skin conditions or health problems. Always talk with your child's healthcare provider for a diagnosis.

First aid for blisters

Blisters often heal on their own. Treatment will vary according to the cause. Some general guidelines for treatment may include:

• Wash the area with soap and water.

• Use a cold pack to help reduce swelling and discomfort.

• Keep the area clean and dry. Don't burst or puncture the blister.

• Use padding as needed in pressure areas.

• If the blister bursts, put petroleum jelly and a nonstick bandage or dressing on the area to keep it clean.

• Watch the area for signs of infection. These include increased warmth, swelling, redness, fluid leaking, pus, or pain. If you see any signs of infection, call your child's healthcare provider. Antibiotics may be needed.

Blisters that don't heal or that keep coming back should be seen by a healthcare provider.