BLISTERS -- Small Spot, Big Deal!

by Liz Wheelan

We all want to explore nature and then put up our feet just to relax, not because they are in pain. In a matter of a few steps, let alone a few miles, even a small blister on your foot can easily swing your thoughts from the joy of fresh air and beautiful surroundings to increasing discomfort felt with each step. For several years I've hiked prepared with traditional Moleskin in my first aid kit but had gone blister free for so long I had a false sense of immunity to this type of injury I'd seen others suffer. That changed recently while backpacking on Isle Royale National Park in Michigan where the views and wildlife are stunning but the high humidity made my feet damp (ok, sweat) while hiking. The experience reminded me of the importance for everyone to take time to learn how to prevent and treat blisters as preparation for your hike, whether novice or veteran and no matter how short or long the trails you plan to take. This article is to provide you with the very basics of the cause, prevention and treatment of blisters, and a few sources with more detailed articles by experts which I would encourage you to review before your next outing.

CAUSES of a hot spot and blister
Boots that don't fit right or are not tight enough may allow your foot to move around too much as you walk. Layers of skin rubbing against each other on the inside of a boot can cause an irritation that makes your skin turn red and is known as a "hot spot". Too much friction can cause the skin layers at these hot spots to separate and fill with fluid and a blister may form. A blister is a pocket of lymph fluid trapped between the skin layers. These simple injuries can be the source of profound discomfort and in the extreme, a trip ending evacuation.

PREVENTION
It is far easier to prevent, rather than treat a blister. Sometimes it's the little steps we take or minutes we spend that make all the difference. Here are some reminders to help you avoid blisters:

Boots must fit you right when you buy them. Don't borrow boots from a friend. Don't depend on a breaking in period to alter how they feel in the store. Try different brands and sizes at different stores.
Go when the store is not busy so the boot expert has time to work with you. Shop in the afternoon or evening since your feet swell during the day. Take the socks you're going to wear so you can match your fit to your own socks, not those provided in the store. Boots should feel comfortable but not allow movement. Your toes should be able to wiggle, but not hit the front of the boot when you walk downhill. Take time to find which boot gives you that "ahhh" feeling when you first try it on.
Trim toenails short and a few days before your hike. Blisters deep under calluses are difficult and sometimes impossible to treat. Reduce calluses with a callus file, without going too deep
Socks, in addition to providing insulation and padding, can disperse friction between sock layers rather than between skin and boot. A smooth, thin, snug fitting synthetic sock worn as an inner layer can move with the foot. The thinner synthetic liner sock will also assist in moisture control by wicking moisture and perspiration away from the skin surface. Let the sock take the friction – they don't get blisters. Never wear cotton socks. Be sure both layers of socks are wrinkle free.
Keep your feet dry. Wet, hot skin blisters faster than cool, dry or slightly moist skin. Wear a liner sock to wick moisture away from your foot – polypropylene, wool or wool-nylon blends work well. Change from damp sweaty socks to dry socks in the middle of the day. Once in camp change socks again if needed and if possible, change into camp shoes so boots and second pair of socks have more time to air. Dry your feet at rest breaks and air your "used" socks on your pack during the day. If they're damp at night, wear them to bed or put them next to the core of your body inside your bag and your body heat will dry them.
Check your feet. Blisters rarely happen without warning and can form in the smallest, most unexpected places. As soon as you feel the slightest irritation or pain, stop. There can be irritated areas on our feet that don't yet hurt, but if the hot spot has our attention, there is a reason for this. We've all probably used the excuse that we didn't want to delay the group. We may have thought we could wait until the next rest break. Unfortunately, by the time we stop, the area "feeling odd" may have turned into a hot spot or worse, a blister, and a small problem has become a challenge to manage. It's good trail behavior to speak up and ask for time to care for your feet. A few minutes spent adjusting your boots or socks, or putting on a piece of tape, to prevent a blister now is much better than dealing with a serious injury later.
Tape trouble spots early. Moleskin has been the gold standard and works well but may be too thick in some instances. Various new medical tapes and blister plasters designed to work on skin work well and reduce the surface friction. These include 3M "Durapore" and Compeed. Blisto-o-Ban, in research they sponsored, has the lowest co-efficient of friction of the foot care products. Moleskin was second best. Be careful you don't develop a blister under the tape, which may turn into a painful open wound when the tape is removed. Paper tape, such as Micropore, usually does not pull off skin and works well under duct or other tape. I'd suggest buying 1 inch wide tape since it's wide enough for larger areas such as the heal, and can be cut smaller for smaller trouble spots.

Research is varied on the value, if any, of moisturizers, lubricating agents and drying powders. Results have shown they may work for a short time, but also may increase the chance of a blister. They should be used with caution and only after your own review of the research.

TREATMENT of hot spots and blisters
There are many different techniques for hot spot and blister care. There are countless differences in feet, footwear, socks, activity and skin – far too many variables to be controlled with one easy solution. I would suggest taking plenty of the basic medical tape, skin grade duct tape, Second Skin, Moleskin and Neosporin. Then supplement that with a few different types of the newer blister bandaids so you can see which product(s) work best for you, keeping in mind that may differ depending on your environment. Opinions differ on when to use waterproof v. breathable tape so also consider its smoothness, stickiness, flexibility and stiffness.

Here are the basic treatment suggestions for:

Hot Spots

Pad with moleskin, duct tape, athletic tape, Elastikon, Hypafix or other medical tapes as a buffer against further rubbing.
Paper tape or a lubricant under the medical/duct tape can prevent the skin from tearing when the tape is removed. The stickier the tape, the more the risk for tearing.
Try any of the modern blister prevention products. Blister plasters, Blisto-o-ban or Band Aid Blister block or similar products works well.

Blisters - Blister Intact

Apply 2nd Skin, Blist-o-Ban or similar product.
Traditional padding cut with an open "donut hole" over the blister works with moleskin. Elastikon, Hypafix and other medical tape tend to be too thin for the donut technique.
Cover with Elastikon, Hypafix, skin grade duct or athletic tape or moleskin.

Blister – Open

Try to avoid draining the fluid if you can since your own skin provides the best healing environment and protection against infection. If the fluid is causing pain or you're worried the blister will burst (usually nickel-sized or larger), then drain it. To do this, clean the blister, then using a needle cleaned with an antiseptic solution or heated until it glows red then is cooled, insert the needle at the base of the blister and let the fluid drain. Apply an antibiotic ointment and cover.
Clean any open blister, which can easily become infected.
Cover with 2nd Skin, Blist-o-Ban or similar product.
The traditional donut hole filled with 2nd Skin or antibiotic ointment still works well with moleskin. Elastikon, Hypafix and other medical tape tend to be too thin for this technique.
Cover with Elastikon, Hypafix or moleskin.

Toe (or other tight spot) Blisters

Blist-o-Ban or similar products can help if the blister is in a spot that's tough to manage with the traditional donut hole technique, such as on or between toes
Paper tape (e.g. Micropore) is thin and can reduce friction of hot spots. Put the tape edges on top to prevent irritation on an adjacent toe. Trim sharp edges or wrinkles. Avoid tight circumferential wraps especially around the foot since it will swell as the day goes on.
Drain the blister if it's rubbing adjacent skin.
Cloth athletic tape, or other tapes with an abrasive nature, can cause blisters on neighboring toes. Save your athletic tape for taping sprained ankles.

A few helpful thoughts
Check all hot spots and blisters for infection at least daily. Beyond these general guidelines, skill in blister care comes from assessing the source of the friction and crafting a barrier to allow the skin to heal. Elastikon, Hypafix and similar products tend to be more flexible than moleskin and athletic tape, and conform to the curves in the foot better. Padding with 2nd Skin, Blist-o-Ban, Band Aid Blister, Compeed or similar products can protect the blister, but too thick a layer is hard to stabilize, and too thin won't protect. Trim tape edges so they lie smooth and avoid wrinkles in the tape. Avoid tape seams ending up between toes or on bottom of toe since this can cause friction and an additional blister. Benzoin can help any tape adhere better and keep the tape from shifting. If using blister plaster, warming it up in the hands thoroughly before applying to the skin can sometimes help it stick more effectively. And unless your blister is infected or the waters too dirty, a foot soak in a cool stream or lake can work wonders.

Closing thoughts
The forgiving nature of modern footwear and synthetic, higher quality sock liners and socks make blisters less common than years ago, but they still can be debilitating and difficult to treat in the field. We used to rely on Moleskin, Molefoam and household duct tape. When Second Skin and skin grade duct tape appeared there were wonderful innovations. Now our first aid kits can be filled with a variety of helpful blister related treatments. Get to know what works best for you so you're able to hike on to that favorite spot and enjoy all that nature has to offer.

For more information and pictures on taping techniques and products mentioned, see Wilderness Medicine Institute of NOLS, WMI Curriculum Enrichment Article - Blisters. Tod Schimelpfenig, Curriculum Director, August 2008, updated February 2009. Also, http://www.nols.edu/alumni/leader/06summer/wildside_of_medicine.shtml

References:

- Scheinberg, S A New Technology for Reducing Shear and Friction Forces on the Skin: Implications for Blister Care in the Wilderness Setting. Wilderness and Environmental Medicine. Vol 17, Num 2. Summer 2006.
- Allen JR., A Study of Foot Blisters. UK: Army Operational Research Establishment, Research Memorandum 1/64; 1964
- Knapik JJ, Reynolds KL, Duplantis KL, et al. Friction blisters: pathophysiology, prevention, and treatment. Sports Med. 1995, 20(3):136-47.
- Herring KM, Richie DH. Friction blisters and sock fiber composition. J Amer Podiat Med Assoc. 1990; 80(2): 63-71.
- Knapik JJ, Hamlet MP, Thompson KJ, et al. Influence of boot-sock systems on frequency and severity of foot blisters. Mil Med. 1996; 161(10): 594-8.
- Vonhof, J. Fixing Your Feet. 4th ed Wilderness Press 2006.