Blisters can occur on any part of the body, but are of particular concern when they develop on the feet. They can cause significant pain, risk of infection, difficulty wearing closed shoes and time away from exercise.

What is a blister?

A blister is a condition of the skin that usually develops because of repetitive friction against the involved area. The friction eventually causes layers of skin to become inflamed and separate. Fluid from under the skin then fills the gap between the layers. The fluid is usually a clear, water-like liquid, but, in more severe causes, can be blood. The amount and type of fluid will vary depending on the location and the severity of the friction that causes the blister. Other types of injuries that can cause blistering of the skin include burns and trauma that “pinches” the skin.

A blistered area of skin can become quite inflamed and painful. The skin on the bottom of a blister is very raw and sensitive. Also the build-up of pressure from the fluid trapped between the skin layers often contributes to the discomfort.

Blisters that result from repetitive trauma can be caused by poorly fitting shoes. Shoes that are too short, too narrow or too shallow will rub against the skin. This may result in blistering of the toes, the back of the heel, or the bunion areas behind the big and small toes. In athletes blisters can form even if shoes are fitted properly. This is because the repetitive stress of exercise and increased perspiration causes the skin to lose some of its natural lubrication, thus increasing the friction.

The best treatment for blisters is prevention in the form of appropriate shoes and socks. Shoes should always be properly fitted and replaced frequently to avoid breakdown of the padding on the inside. There should never be any area of the shoe that is causing too much pressure against the skin. Modern shoe materials generally do not require a break-in period. Shoe that cause irritation even while trying them on in the store should be avoided.

Modern sock materials also help to avoid blisters by helping to keep the feet cooler and dryer. These synthetic materials are designed to wick perspiration from the skin to the outside of the sock. The old adage about wearing white cotton socks is no longer true. Cotton soaks up moisture like a sponge and holds it right next to the skin. Over time this actually increases the chances of blister formation. The best materials are those found in specialized sports socks, such as those for running, hiking and basketball.

Why are blisters potentially serious?

Most people don’t realize that a blister can become infected. When a blister first forms the fluid inside is clean and sterile. However, many types of bacteria live on the skin, especially on the feet.  The bacteria can then penetrate a blister and cause an infection.  A blister that’s not infected is tender enough, but one that gets infected can be exquisitely painful! Blisters commonly appear inflamed, but infected blisters will become bright red around the outside and can even cause red streaking up the foot or leg. In severe cases infected blisters can cause a person to become physically ill with fever and chills! Blisters should definitely not be ignored, especially on the feet.

What is the best way to treat a blister?

Whether or not to pop the blister is always the question. In general it is not recommend for you to pop a blister on your own. This type of bathroom surgery can lead to nothing but problems. However, if a blister is “popped” using a sterile instrument within the first few hours, the skin can often be held back down with a compression bandage. This should alleviate the pain and risk of infection.

Unfortunately blisters usually aren’t treated early enough to allow the skin to re-adhere. The lifted skin on the surface of a blister essentially becomes “dead skin”. This creates a problem because the bacteria in the area thrive in this environment. They are able to penetrate a popped blister, multiply, and then cause an infection.

There are two primary choices for treating a blister. If the blister is small and not painful it can be allowed to heal on its own. In most cases the inflammation will gradually decrease and by the time the dead skin sloughs off the skin underneath will be healed. However, for larger or more painful blisters, or those that appear to be filled with blood medical treatment is strongly recommended. All of the skin from the top of the blister should be removed, the area cleansed, and topical antibiotic bandage applied.

No matter how a blister is treated it should always be closely observed for the possibility of infection. A topical antibiotic, i.e. Bactroban, should be used on the area and it should be kept covered until the skin underneath is completely healed. The causes of the blister should be carefully evaluated in order to avoid having the problem recur at the same location.

Richard H. Graves, DPM
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Podiatrist, Sports Medicine Specialist