Blisters are a common complaint and here we discuss how they occur and the treatment necessary.


A blister is a small pocket of fluid in the upper layers of the skin. Most blisters are filled with a clear fluid called serum. Serum is the part of the blood that remains after red blood cells and clotting agents have been removed.

Clinical Signs and Symptoms

Blisters are generally oval in shape and are filled with bubbles of serum.

Blisters are sometimes filled with blood (called blood blisters) or pus (if they become infected).

The skin of the blister changes colour and will leak serum and / or blood if pierced.

Blisters are generally painful, particularly when the skin is pierced or removed, which then leaves the underlying tissue exposed to infection.


Traumatic blisters are caused by friction over time e.g. rubbing within a shoe, however, there are several other causes that need to be kept in mind e.g. chemical or heat burns (sunburn and scalds) and medical conditions e.g. chickenpox and impetigo.

Certain groups are particularly prone to traumatic blisters:-

  • Distance runners.
  • People wearing tight shoes or inappropriate footwear.
  • Females wearing high-heels with narrow straps around the heel.
  • People who have a foreign body in their shoe.

Treatment / Patient Advice

Those that will be doing long distance including marathon runners and hikers should use protective coverings such as duct tape/moleskin or the use of petroleum jelly. These have been proven to reduce shearing and frictional forces. All shoes should be “broken in” before wearing them for long periods.

After the activity has ceased the footwear, socks and any protective coverings should be promptly removed so that the feet can be thoroughly dried and inspected for signs of injury.

The best treatment for minor blisters is to leave them alone, as they will heal naturally. According to NHS Choices (2009) the fluid that collects under the damaged skin cushions the tissue beneath. This sterile fluid protects the tissue from further damage and allows it to heal.

If blisters are significant and very painful then please see one of our Podiatrists for drainage and for the area to be dressed. Please phone The Footcare Centre on 01932 849373 or book online.

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