By Veronique Hauschild, Environmental Scientist, Army Public Health CenterSeptember 2, 2015
Most of us have experienced the pain of having a friction blister. Friction blisters form when an object (such as a sock, shoe or strap) is repeatedly moved across the skin with enough force to cause the layers of skin to release heat. The heat causes redness and a separation (or 'cleft') between the outermost layer of the skin and rest of the skin layers. The cleft fills with fluid causing a raised area on the skin. They typically form on the toes, feet and ankles but can also occur on the hands or other places where there is repeated rubbing (such as on the torso from the straps of a heavy backpack.)
Because these injuries often only cause discomfort and don't require medical treatment, they are sometimes described as "just a blister." However, some blisters become serious and temporarily debilitating for Soldiers and athletes. Blisters can force you to restrict your activity and limit physical training. In some cases, friction blisters develop into infections that require antibiotics and medical treatment. As one of the most common injuries among active duty military, friction blisters can have a notable adverse impact to military readiness.
Activities such as marching and running are the most common causes of blisters in the military. A recent review of injuries associated with marching or hiking showed that heavy load carriage increases your risk of foot blisters. You may not be able to avoid activities that put you at risk of developing blisters. However, there are things you can do to minimize the likelihood of developing a blister and/or reduce the severity of any blisters you develop.
You may already be aware that some individuals are more prone to develop blisters than others who perform the same activities. While the science is not substantial, studies do provide evidence that some people may have a higher risk of developing blisters. For example, having no foot arch or flat feet, or being of an ethnicity other than African American/Black, can increase your risk of getting a blister. While these factors cannot be changed, other factors that increase risk of blister can be modified. For instance, wearing cotton socks, especially if socks or feet are moist, and using tobacco (including smokeless tobacco) can increase chances you develop blisters.
In addition, various "best practices" for preventing blisters are also recommended by medical professionals and professional and amateur athletes. While there is limited scientific evidence validating the effectiveness of most tactics among large populations, try some of the tactics below to determine what works best for you in avoiding the pesky but painful blister!
Start with this (best supporting scientific evidence):
Start slowly and build up to activity and equipment To help your skin become more resistant:
• Increase duration and intensity of blister-causing activities slowly over time.
• Use the same shoes, gloves or load weight/shape as you increase activity.
Use synthetic moisture wicking blends (no cotton) Keep skin dry:
• Synthetic socks made from acrylic, nylon or polyester that ventilate and wick moisture away from the feet are recommended over cotton socks, to prevent blisters, especially during long distance marching or running.
• Some people advocate wearing a double layer of socks (non-cotton), since a second layer stops the first from rubbing against the skin. However, others prefer a single layer loop-stitched sock, as less heat is generated than with 2 layers. Scientific evidence does not clearly indicate which is best -- this may vary with individual risk factors.
Consider other options:
Ensure proper fit and maintenance Minimize contact between your foot and shoe:
• Make sure toes do not touch end of shoe while walking, and consider a wide toe box with room for toes to wiggle.
• Purchase shoes later in the day since foot size may swell half a size throughout the day or after activity.
• Do not leave shoes/boots on radiators or near heaters since this can cause them to shrink and seams to protrude.
TAPING AND SKIN COVERINGS (Specific products to stick with you for hours):
• Certain skin coverings have been shown to help absorb friction during movement which can reduce blister occurrence or severity.
• Zinc Oxide tape has been anecdotally reported in running communities to prevent blisters from forming or minimizing further injury to an existing blister. Other products referred to as "blister plasters" will expand in response to friction and thus protect the area from blisters forming or getting worse.
Less or no supporting scientific evidence:
• A closed-cell neoprene insole was found to reduce the incidence of blisters in U.S. Coast Guard recruits.
• Anecdotal reports suggest properly fitting insoles can reduce blisters, though ill-fitting insoles can increase them.
COATINGS (Reduce friction with various coating products):
• Inexpensive products, such as petroleum jelly, used to coat areas to reduce friction and prevent chafing and blisters have been commonly advocated by various athletes to prevent blisters on feet, under arms, bra straps or between legs.
• While prior study suggested antiperspirants may reduce blisters, there is a risk of skin irritation, so it is not specifically recommended. Potentially less irritating coatings include products such as "Vaseline," or of more recent popularity, longer lasting non-oily coatings such as "BodyGuide." Anecdotal reports suggest these products prevent blisters without causing skin reactions, but no scientific study has validated their effectiveness.
(Use of trademarked name does not imply endorsement by the U.S. Army, but is intended only to assist in identification of a specific product.")