First Aid

First Aid Fridays: So There’s a Crater in Your Foot

This article is part of a series on Wilderness First Aid called First Aid Fridays. Skip to another post:


Blisters. Boring and easy subject, right? That was the assumption I had when I began preparing for this article. Little did I know I was about to find myself ankle deep in a swirling torrent of sock liners, foot creams, and padded insoles.

I found dozens of articles, websites, and blogs giving advice on how to prevent these pesky little things, but I wanted to get past the advice and find information that was actually well supported by research. Separating myth from reality turned out to be very challenging.

Sadly, medical literature on blisters seemed to be seriously lacking. The best study I could find on blister care was from 1955. I didn’t want to cite a study conducted in an era when frontal lobe lobotomies were all the rage and children’s cough syrup still contained opium.

When I changed tactics and began searching through military studies, I realized most of the relevant data on foot care for active people has been done on the battlefield. Considerable time has been spent trying to figure out how to keep soldiers from getting blisters on long marches in heavy boots.

I’d hit the goldmine – suddenly I had an overwhelming amount of research at my toe tips. Thank you to all of those soldiers who had to trek in uncomfortable footwear to provide us with this information. Your foot pain wasn’t endured in vain.

I’ve decided to list prevention methods in the following order: From those that are the most well supported and practical, to those that have very little data behind them and may actually be detrimental.

Recommended Methods:

Wear Proper Footwear

When you buy new shoes, take special care to find the right fit. They should feel comfortable when you put them on. Some breaking in will be necessary, but avoid shoes that feel like they are pushing your feet into an unnatural position or squeezing any part of your foot.

Try on shoes with the socks you normally wear during your outdoor activities, not the loaner socks the store provides. There should be 0.5 – 1 inch between your longest toe and the end of the toe box. Buy a new pair of shoes as soon as your old ones start to become uncomfortable.

Break in Your Shoes Gradually 

New boots were found to be a major culprit behind blisters in one study. As much as you may love a new pair of shoes, do not take them twenty miles on their first outing. Start by wearing them at home while doing chores for a few hours, then wear them around town, and finally take them on a short hike before you bring them on longer treks.

Choose Socks Wisely

Merino blend wool socks are the most effective at reducing moisture. Pair them with a thin polypropylene liner that will wick the sweat away from your feet. When your socks become extremely moist, change them. See this article by Max for more information on choosing socks.

Condition Your Feet 

Everyone’s skin is different, and some people are just more prone to getting blisters. But skin can also be conditioned gradually to build up it’s resistance to the forces that cause them. I’m not talking about running barefoot until you get calluses, as these don’t actually prevent blisters and may actually lead to worse ones.

You are much more likely get blisters if you increase your activity drastically over a short amount of time, like running a half marathon one day when you usually only run a few miles. Increase your activity gradually to protect your feet.

Use Tape

Kinesiology tape can be applied directly to blister prone areas for prevention, like the skin between your toes. The aim of tape is to decrease the friction acting on your foot, so a good tape should be very sticky on the inside but not on the outside. It should stabilize the skin while still allowing it to slide slightly against your sock.

There are many great tapes out there, but I find RockTape to be the strongest and most sweat resistant. Taping correctly can be challenging; take a look at John Vonhof’s book Fixing Your Feet: Injury Prevention and Treatments for Athletes for some great photographic references.

Engo patches are an alternative to tape that are applied directly to irritating places in your shoes rather than you feet. They are easier and faster to apply and are very handy to have around.

Questionable Methods


A large study using U.S. Military Academy cadets as guinea pigs found that deodorant applied to the feet nightly reduced blister formation considerably. However, the deodorant also caused a high rate of skin irritation among the cadets. The study was fairly limited in its scope and methods.


Lubricants decrease the amount of friction between your foot and your sock, but only for about the first hour. Within three hours, they actually increase friction. They must be wiped off and reapplied frequently to remain effective.


I found many, many sites suggesting rubbing everything from cornstarch to expensive mineral compounds into your feet. Some runners swear by foot powder, and if it works for you, great. I could not find any evidence supporting its use. In fact, several (admittedly very dated) studies conducted in the British military suggested powder may actually cause more blisters.



Once a blister has formed, Moleskin can reduce the discomfort and prevent it from worsening so you can keep on trekking. Cut a piece larger than the blister, and cut a hole in the center for the blister to fit through.

To Pop or Not to Pop?

If you’re a sicko like me, popping that fluid filled bleb can seem so tantalizing. But in the wise words of the great Ice Cube, chickity check yo self before you wreck yo self – popping blisters can lead to infection, especially if you’re out in the backcountry. The top layer prevents the sensitive inner layer of tissue from becoming exposed to bacteria. Avoid it if possible.


Sometimes a blister just has to be popped due to its size or the irritation it’s causing. If you’ve decided this is the proper course of action, get a needle or a scalpel. Clean the area thoroughly. Make a small hole in the  side of the blister and gently press all of the fluid out. Apply antibiotic ointment and a pressure dressing to adhere the layers of skin together and prevent it from filling with fluid again. If the blister is filled with white or green fluid, that probably means it’s infected and should be seen by a medical provider.

Sources and Further Reading:

The Blister Prone Athlete’s Guide To Preventing Foot Blisters by Rebecca Rushton

Fixing Your Feet: Injury Prevention and Treatments for Athletes By John Vonhof

Blisters: First Aid, Mayo Clinic

The effect of two sock fabrics on perception and physiological parameters associated with blister incidence: a field study.

Blisters on the battlefield: the prevalence of and factors associated with foot friction blisters during Operation Iraqi Freedom I.

Influence of an antiperspirant on foot blister incidence during cross-country hiking.

How to Break in Your Hiking Boots

Podiatry Today: How to Manage Friction Blisters 

Boring but Necessary Disclaimer:

This is not a substitute for professional medical care. First aid is meant to provide assistance to an injured or ill person when medical treatment is unavailable. Do not delay seeking professional help in the event of a serious condition.

If you are interested in learning more about Wilderness Medicine, I recommend enrolling in a Wilderness First Aid course through your local REI.


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