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Dr. Pribut On Friction Blisters: Prevention, Treatment, Cause

Moisture, Friction, Heat Must Be Beat!

by Stephen M. Pribut, DPM

Blisters are believed to be one of the most common sports injuries. Left untreated, they can significantly impair performance, alter your gait, and result in discomfort, pain and infection. However, only rarely will they result in a serious interruption of training. An online survey (Pribut, 2002, Internet revealed that only about 0.5% of all injuries which resulted in a one week interruption of training were caused by blisters.

painful blisterBlister

Prevention and treatment of blisters is still an important issue. From fingers to toes blisters can interfere with athletic performance. From a baseball pitcher with a blister on his hand to a runner with a blister on a toe, these unwelcome skin injuries can cause a missed start for a pitcher or a slow and painful run for the runner.

Contributors to friction blister formation

A combination of moisture and friction leads to blisters. Friction combined with excessive moisture sets up the right combination for blister formation. A cotton sock is like the iceing on a cake for blisters. Cotton holds the moisture against your skin and doesn't allow it to wick and move away. Cotton loses its cushioning and compresses when wet.

Sweaty palms and fingers need to be avoided as much as possible with those participating in pitching or racket sports. Runners should avoid soggy socks and ill fitting shoes. Synthetic materials with moisture wicking capacity are important for athletes who run. Performing endurance sports in new shoes or new socks can also contribute to blisters. Blisters occur most often in areas of friction and rubbing. Make sure this is minimized. For chafing from clothing, try to avoid the clothing that rubs. Even jock straps can cause chafing in hot weather on a 20 mile run. Try alternative clothes. Thighs that rub together can cause chafing, irritation or blisters. Body glide and similar products can help.

The worst blister story I've heard of was reported in the New York Times July 8, 1924. Calvin Coolidge's nearly 16 year old son developed a blister on his big toe reportedly after playing tennis on the south lawn in shoes while not wearing socks. Several days later the blister became infected, he developed septicemia and died within the week. This is not something I'd expect to develop often, but diabetics with neuropathy and lessened sensation are at risk for significant problems, including infection and ulceration. Even a minor problem such as a blister could turn into something much more serious.

Contributing Factors




Ill fitting shoes

New shoes, socks, clothes

Unaccustomed activity


What is a blister?

A blister is actually a separation of the epidermis from the dermis or a separation within the epidermis itself. Vesicle is the term applied to very small fluid filled bubbles and may occur in conjunction with athlete's foot. Bulla is the medical term used for "blister". Most often the fluid within the blister is clear, but on occasion there is bleeding into the blister ( a blood blister) and it is bloody.

Blister Prevention Tips

Some have recommended vaseline or other moisturizers to prevent blisters. As a gooey and occlusive (non-breathing) material I do not recommen this. When moisturizers are used, they can be helpful in the short run, but after an hour there is an increase in friction present. I would not recommend trying it for the first time in a marathon. Go with what has worked in the past - and in particular good fitting, broken in shoes, with socks that wick moisture well. If you are running or hiking and notice a "hot spot" you may apply moleskin or other padding to decrease friction.

Wickability is the key feature for sport socks

A wicking gradient allows moisture to evaporate from the foot. This wicking gradient requires a breathable shoe upper. Hydrophobic characteristics of socks are not the determinant of wicking. (i.e. polypropylene). The mechanical structure of the fibers plays a large role with wicking tubules being a helpful construction. The material should not overly compress, as cotton does.

Both cotton and wool both swell between 35-45%. Cotton in particular will also hold moisture, lose its shape and compress irregularly. Wool, will allow moisture to leave the foot. Acrylic only swells 5% and allows moisture to drain and move with 2.4 times less resistance than cotton. Cotton holds 10 times the moisture of Coolmax and loses its shock absorption characteristics when wet.

Wicking assists thermoregulation. By pulling the moisture away and allowing evaporation cooling is effected in hot weather. And by allowing it to wick, heat retention is assisted during cold weather.

Treatment of friction blisters

The skin over the blister itself provides protection from bacteria in the environment. It is like a raincoat for the skin. It does not always need to be punctured. A small blister may just be allowed to heal by itself. Sometimes you will need to have a blister punctured to reduce pressure on the underlying skin. (If you are diabetic you may need to have pressure from a blister reduced. This should be done in a doctors office or emergency room.)

Needles and pins can not be properly sterilized at home. No one would heat either of these at home and then use them to perform surgery in an operating room. I recommend getting a packaged sterile needle from a pharmacy and using that to puncture a blister, if necessary. The hole should only be in the upper and separated layer of skin. You should not go too deep and poke a hole in the underlying good skin. You can cause a bad infection by going too deep. Do not peel off the overlying separated skin. It is protection and acts as a biological dressing. You should apply a non-greasy, and non-gooey dressing in most cases. Betadine (povidone-iodine) liquid and a dry gauze pad works well.

The unofficial, and not entirely safe description for needles and pins is: heat a pin or needle over a flame until it glows red, allow it to cool and then carefully puncture the blister close to its edge. Apply gentle pressure to allow the fluid to drain. After you have punctured the blister and drained much of the fluid, you should not remove the protectective cover of skin. This skin acts as a biological dressing and will also reduce irritation on the raw tissues beneath. You should then apply an antibiotic cream or an antiseptic such as Betadine (povidone-iodine) and a sterile gauze as a dressing. Moleskin or tape applied to a blister will cause all of the skin to peel off along with the dressing.

If there are bony prominences on your foot either on the toes or the heels, padding may be used to minimize repetitive friction and pressure.

Diabetics and individuals with impaired circulation should not self-treat blisters, but need to seek professional care. The rest of you should be careful to try to avoid infection and to observe carefully for signs of infection, such as redness or red streaks around the periphery of the blister, pus within the blister, and increasing pain or heat. The cardinal signs of infection are redness, heat, swelling, and pain.


Background Information:

Review of The Function of Skin

Primary Functions

Protection from injury

Keep fluids inside in, and outside out
Resist microbial penetration
The largest sensory organ

Secondary Functions

Immunological Protection

Solar energy protection (UVA and UVB)
Assist in Vitamin D metabolism

Functional Adaptations of Skin

Rocky Trail

Eccrine sweat glands
Appocrine glands
Sebaceous glands

Vesiculo-Bullous Disorders Ddx

Drug Reaction
Erythema Multiforme Bullosa
Epidermolysis Bullosa
Bullous Lichen Planus
Porphyria cutanea Tarda
Cat-scratch disease
Dermatitis herpetiformis
Erythema multiforme
Herpes simplex
Herpes zoster
Porphyria cutanea tarda

Outline of causes of friction blisters


About Dr. Pribut: Dr. Pribut is a member of the Advisory Board of Runner's World magazine. He is a past president of the American Academy of Podiatric Sports Medicine (AAPSM). He served as chair of the AAPSM Athletic Shoe Committee for 5 years and has served on the Education Committee, the Research Committee, the Public Relations Committee and the Annual Meeting Committee. He is a co-Editor of the current AAPSM Student's Manual. Dr. Pribut is a past president of the District of Columbia Podiatric Medical Association, serving in that post for 4 years. Dr. Pribut currently is a member of the American Podiatric Medical Association's Clinical Practice Advisory Committee. Dr. Pribut is a Clinical Assistant Professor of Surgery at the George Washington University Medical Center.

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