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Cotton Kills: Why Is Cotton Bad For Hiking?

"Outbound" Dan Human has been drinking out of streams, ponds, and puddles for several years on various backpacking and paddling trips.

Sorry folks, the trail is closed.  You'll have to come back when you are properly dressed.

Sorry folks, the trail is closed. You'll have to come back when you are properly dressed.

Cotton Kills Hikers

If you haven't heard the outdoor adage "cotton kills," pay attention and you may just save your life. Sure, cotton is fine to wear while shopping for groceries and looking "outdoorsy," but wear it in the great outdoors and it may kill you.

Every outdoor organization from the Boy Scouts to The Mountaineers warns vehemently against wearing cotton while hiking and backpacking. Despite multiple warnings from these experts, people perish each year from inadequate preparedness whilst in pursuit of outdoor adventure.

A guide friend of mine is so anti-cotton that he inspects each garment of everyone he is taking into the backcountry. He's been known to say, "take in an ounce of cotton, and pack out a cold body." A bit dramatic, yes—but is it well founded?

While teaching backpacking classes, my favorite illustration of the dangers of wearing cotton is to soak two pairs of pants—jeans and supplex hiking trousers—and let them sit out overnight. In the morning, the class gasps as the jeans creak and moan as I bent their frozen form in half. Meanwhile, I just shook the ice crystals off the hiking pants.

So which would you rather wear?

Cotton by Other Names

  • Denim
  • Duck
  • Flannel
  • 50/50 blends

Hypothermia: How Cotton Kills

Wearing cotton doesn't leach dangerous chemicals into your skin or make you more prone to being mauled by a rabid beaver; it kills through hypothermia. Hypothermia is a condition in which the body's temperature falls below 95 degrees; it results in death when untreated.

Most people think that hypothermia only happens while digging through five feet of snow, but often it occurs to unsuspecting hikers during marginal weather in the warmer months. According to Mountaineering First Aid, "Many hypothermia cases are reported in wet, windy weather with temperatures well above freezing."

Winter backpackers are usually prepared to combat freezing temperatures with multiple layers of technical clothing. Conversely, summer backpackers and hikers often skimp on warm extra layers and may wear inappropriate clothing that dries slowly and loses its thermal properties (cotton).

Wetness Equals Death

The major problem with cotton is that its hydrophilic nature causes it to dry very slowly and absorbs moisture like a greedy sponge. Conversely, materials like synthetics and merino wick moisture away from the skin and to the outside of the garment, where it evaporates.

So what does it matter if your cotton shirt is soaked?

According to the Appalachian Mountain Club, some forms of cotton absorb up to 27 times their weight. As a backpacker, you need to think carefully about anything that gains weight while outdoors. Like I said, cotton is a sponge.

Wet clothing conducts heat away from your body 25 times faster than dry clothing, so wet clothing (that favorite t-shirt of yours) is a recipe for contracting hypothermia.

Cotton: It's comfy when dry,

And cheap to buy.

But to wear it in winter,

It's a good way to die.

— John Dunn, "Winterwise"

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Read More From Skyaboveus

Rain Droplets on Cotton

Notice how the rain droplets soak into this cotton shirt.

Notice how the rain droplets soak into this cotton shirt.

Rain Droplets on Synthetic Shirt

As the rain begins to fall, rain droplets bead up on this shirt from Mountain Hardwear.

As the rain begins to fall, rain droplets bead up on this shirt from Mountain Hardwear.

Loss of Thermal Properties

Cotton is an outstanding insulator while it is dry; that's probably why we love flannel sheets on our beds. However, once cotton becomes wet, it loses 95% of its thermal properties. Yes, it will make you colder - a lot colder.

On the other hand, most specialty hiking clothing retains its insulating properties while it is wet. I've been submerged in streams slightly above the freezing point, but was fine due to the technical clothing that kept me warm while wet.

If you do insist on wearing cotton while hiking, you should carry several additional layers to change into when your clothing becomes soaked.

Hoodies Are Most Often Cotton

In a survey of my local outfitter, I found that 90% of hoodies are made of cotton. This is unfortunate, because the hoody is a favored garment for warmth, especially amongst the younger crowd. If you love the style, check out Under Armor's synthetic hoody selection.

What Happens to Jeans When They Freeze

When to Wear Cotton

Besides wearing for casual use, does cotton have a place in the outdoors?

Many desert hikers extol the virtues of cotton while trampling through arid climates. The sweat from their body soaks the cotton shirt and the gradual process of evaporation cools their bodies during the day. As the cool desert night air drifts in, hikers switch to dry clothes to avoid hypothermia.

Still other desert dwellers dislike the clammy feeling of wet cotton as they hike, so they prefer to wear synthetics. Though cotton has great UV blocking qualities, many treated garments like Omni-Shade from Columbia are better than cotton at protecting you from the sun. Even the Skin Cancer Foundation recommends those sun blocking materials.

Comfortable Alternatives to Cotton

Though some people like to wear cotton because "it is comfortable," they haven't worn some of the newer materials which are more comfortable, wick better, and dry faster.

  • Synthetics

A synthetic hiking shirt is an awesome thing to have, though some people will balk at the expense. I've had one shirt from The North Face that has lasted over 16 years. It thru-hiked the Appalachian Trail with me, climbed mountains, and bike toured across two states. Talk about rugged construction.

Currently my favorite shirts are the Wicked Light shirts from Mountain Hardwear. It is awesome to hike all day and have a dry shirt at the end of it.

  • Merino Wool

In the early days of hiking, trekkers clad themselves from head to toe in wool—a renewable fiber that retains most of its thermal properties even while wet. As synthetics grew in popularity, people ditched the itchiness and weight of wool.

However, then companies started using Merino wool, a non-itchy super-comfy wool which keeps you warmer in winter and cooler in summer. Though many people love Merino socks (myself included) my favorite long-sleeved shirt is made from Merino by SmartWool. I have worn it for days at a time.

  • Cocona

Cocona comes from the husks of coconuts. Now that sounds comfortable doesn't it? Actually it is. After coconuts are shelled, the husks are converted into activated carbon (also used for water filters) and then bonded to fibers for use in clothing.

Cocona products are very soft and comfortable, plus they have excellent technical benefits. I've found that my shirts made with cocona dry faster and have better moisture management than most other hiking shirts. Though antibacterial treatments can wash off, cocona's benefits are renewed when you wash them, which makes it a very sustainable garment.

A Few Examples of Tragic Outdoor Deaths

Nobody ever said hiking was safe, but here are a few examples of hikers who perished in the wild. Wearing cotton clothing seems to be a factor in each unfortunate example.

In September of 2008 a hiking party on the Pacific Crest Trail near Tinker's Knob encountered rain and high wind speeds, despite a sunny start to their trip. One hiker died and three others were rescued. A responding SAR team representative credited the tragedy with, "They had gotten separated, and they were wearing cotton, which takes forever to dry." (Source: "Exposure suspected in death of Pacific Crest Trail hiker" by Barbara Barte Osborn.)

One of the earlier examples from the Adirondack High Peaks happened during a tragic Thanksgiving weekend. Despite having a new complement of "appropriate gear," two hikers were clad in all cotton. After getting waterlogged in an overly ambitious pursuit, an exhausted hiker with soaked cotton clothing succumbed to a hypothermic death before help could arrive. (Source: "Thanksgiving Weekend Death in the High Peaks" by Princeton Outdoor Action.)

In September 2005, a man hiking in the Alaska Range near Fairbanks died from the effects of hypothermia. A state trooper was quoted, "He was wearing all cotton, which is the worst fabric for cold, wet weather. ... The weather just got the best of him." (Source: "Body of Wyoming Hiker Recovered From Alaska Range," AP.)

A Simple Hiking Clothing Experiment

Two shirts out in the rain, my experiment.

Two shirts out in the rain, my experiment.

So I read the accounts and experienced the lack of comfort in cotton-clad hiking, but was there a quick experiment I could do?

I glanced at the rain droplets gathering on my kitchen window and had an idea. I took two shirts, one lightweight cotton and one synthetic, and placed them on my lawn in a light rain. I let them sit for 40 minutes for a good old-fashioned soaking.

I wrung out both shirts as best I could, hung them on a line in an unheated area of my basement, and watched them dry. Watching a couple of shirts drip dry is slightly more exciting than waiting for the grass to grow, but a sacrifice in the name of "science."

The Mountain Hardware Wicked Lite synthetic shirt was dry within 3 hours.

The cotton t-shirt, a giveaway from National Trails Day, took 6.5 hours to dry.

The verdict: specialty hiking clothing dries more quickly than cotton. Given the facts that wet clothing creates heat loss and that cotton loses thermal properties while wet, cotton seems to be the loser in my mini-experiment.

A Comfortable Hiking Clothing System

Part of a comfortable hiking clothing system: North Face convertible pants, a Mountain Hardware fleece and t-shirt.

Part of a comfortable hiking clothing system: North Face convertible pants, a Mountain Hardware fleece and t-shirt.

So what do I wear for three-season hiking in the Northeast?

I always think of clothing as a system, and as the most technical part of my gear. This is generally what I carry.

  • Shell Jacket: The North Face Verto (water and wind resistant)
  • Warmth: EMS microfleece (zip neck)
  • Shirt: Mountain Hardware Wicked Lite t-shirt (one every three days)
  • Pants: EMS Supplex convertible pants/shorts
  • Shell Pants: Sierra Designs Microlight windpants
  • Boxers: Ex Officio Give 'n Go boxer briefs (one every two days)
  • Socks: SmartWool medium hiking socks (one pair per day)
  • Warm hat: Mountain Hardware neck gaiter
  • Glove: Seirus Hyperlite gloves

So Will Cotton Actually Kill You?

One of my hiking companions.

One of my hiking companions.

Before accusing me and the entire outdoor industry of sensationalist hyperbolic claims, let's look at cotton one more time.

The fact is, many new and old hikers alike venture into the wild with cotton clothing and return unscathed. However, wearing non-cotton clothing is safer.

As part of risk management, you can't eliminate all risk, but you can make things safer. Surely, nobody plans on twisting an ankle or taking the wrong trail, but you can plan what you wear. You will have a safer and more comfortable time in the outdoors if you wear non-cotton performance hiking clothing.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

© 2012 Dan Human


Rachelle Williams from Tempe, AZ on February 27, 2020:

Whoa! I will never forget this advice:

Cotton: It's comfy when dry,

And cheap to buy.

But to wear it in winter,

It's a good way to die.

— John Dunn, "Winterwise"

Marie on May 28, 2018:

Really appreciate this info.

magali on July 02, 2017:

Please can you make a post on oyher fibers like silk and linen. Thanks so much for such an informative post!

Lupe from South Texas on May 10, 2015:

Awesome information. when I was Stationed in Fort Drum, Cold weather raining was a big thing, Not so much in Hawaii though, We would have death by Power Point training all the time. But in the end, it was good information that will save your life. Layer-Up and stay Hydrated = #HappyTrails and #SafeOutDooring Thanks Dan!!

Ryan from Manchester on May 05, 2015:

Fantastic Hub, gave you a thumbs up! Keep up the great writing.:)

J.M on April 15, 2015:

Good to know.

Ed Palumbo from Tualatin, OR on March 26, 2015:

W, Do you hike and camp in moist or wet weather in freezing or nearly freezing temperatures? If not, this is not a major concern for you. You may observe that cotton jeans or gym clothes do not retain heat and will not keep you warm when wet. If you fall through ice and find yourself in waist-deep water, as I have, those jeans will wick away body heat in very short order. In that situation, wool will continue to insulate you but cotton will not, and hypothermia is a deadly adversary. I'm glad you miraculously survived just fine.

W on March 25, 2015:

I had no idea how lucky I've been - nearly 50 years of hiking, camping and backpacking in cotton jeans - and - miraculously - I survived just fine.

Carrie Lee Night from Northeast United States on February 07, 2015:

Learned something new and valuable today :) Thank you for sharing !

NewHiker on January 25, 2015:

I heard something like "cotton kills" from an experienced hiker and bought a pair of hiking pants (made of nylon) - it's light, it's waterproof, it's tough. However, man, that almost "killed" me! Those "hiking pants" don't breathe and my lower body was soaked with sweat - this unexpected excessive sweating led to rapid dehydration, and I was stuck in the middle of a national park almost unable to move. Back to cotton jeans which keep my ass dry - that's perfectly fine for a day-hiker like me.

Ellen Gregory from Connecticut, USA on January 16, 2015:

I found this information fascinating. It's perfectly logical and yet I never thought of it. This will change what I pack for my Alaska trip next year.

Ellen Gregory from Connecticut, USA on January 16, 2015:

I found this information fascinating. It's perfectly logical and yet I never thought of it. This will change what I pack for my Alaska trip next year.

Glenn Stok from Long Island, NY on December 29, 2014:

I'm an avid hiker but this is something I did not know. Just two weeks ago I hiked on a cold winter day and I realized I was all sweaty after walking 7 miles at a fast four mile-per-hour pace. Of course I was wearing cotton and now I know better. Thanks for the education from this well written and informative hub.

Adam on December 29, 2014:

great article. knew cotton wasnt the best option, but didn't realise it was that bad. jeans and cotton pants were always off my list as well as hoodies, but never knew a cotton tshirt would be so bad. even with thermal base layer? gearing up for the milford track next year here in NZ and its known as a very wet area, so good advice

yehring on December 01, 2014:

A lot of good information, but hate the phrase. Cotton has no more ability to kill than Teflon products breath. If you understand the limitations of cotton, then there are numerous applications for outdoor use. None of which would include high aerobic activity in cold weather however.

A couple technical issues with what you wrote:

1. The body does not conduct heat 25 times faster when wet than dry. Water has 25 times the thermal conductivity of air, so heat loss from the body is 2-5 times more quickly when wet than dry. 25 times faster is ridiculously fast and completely negates the efficiency of the human body in preserving heat. Its been miss-stated for a long time. These facts are from full immersion in cold water, not just wet clothing. Essentials of Sea Survival, Golden and Tipton. Best read on hypothermia and how the body loses heat there is.

2. Synthetic materials don't wick moisture away from the skin to the outside layers where it evaporates. There is so much wrong about this I don't know where to start. Synthetics wick by spreading out water molecules (water) so that the heat pump action of the body can convert it to water vapor again so that it can then evaporate or escape. A strong temperature differential from inside the clothes and outside make this process more efficient. The idea is not to sweat where your producing water, but to regulate clothing to keep it at the vapor level. That's where the efficiency of synthetics really come into play. Haven't figured that out for snowshoeing or Nordic skiing yet but that's the idea. The idea of breathing comes from vapor (not water) being able to escape your clothing due to the heat pump action of your body. Without that, the vapor stays. It doesn't get sucked out of your clothing by this idea that it breaths. Thank you Gore-Tex for coining that stupid phrase to describe this process. Cotton, as you stated, saturates water, doesn't allow it to spread out, and thus doesn't allow the heat pump of the body to return it to vapor and evaporate or escape. Synthetics have limitations too. Trying wearing nylon next to the skin while your sweating and you'll know what "cold soak" means. Nylon takes on the temperature of the surrounding air and when its wet and next to the skin, it can be a painful experience. Back to my original statement of knowing the limitations of your gear.

Thanks for the topic awareness, very well written, and very much appreciate the effort in getting the word out.

Elsie Hagley from New Zealand on November 24, 2014:

Interesting reading. I always thought that cotton was excellence fabric as it's cool in the heat and it warms you in the cold. This article is the first time I have heard about it like this. It has made me stop and think about the subject. Thanks for sharing.

Suhail Zubaid aka Clark Kent from Mississauga, ON on November 24, 2014:

Great hub, Dan! Unfortunately, I learned the hard way. Adventuring in the deserts of the UAE (intermittently from 1996 to 2003), I found the disadvantages of cotton. Even though cotton gave a nice wet cool feeling till the sun was up, it soon led to cold effect. Changing the shirt and carrying extras was another hassle.

There is still so much of new information here that I can put it to good use. I believe a trip to outdoor adventure stores is due now.

Thanks again for writing such an informative hub as this one.

Dan Human (author) from Niagara Falls, NY on November 23, 2014:

I am really falling behind in responding to my comments - thanks to all who have read and took the time to comment upon my article. I greatly appreciate it.

Even for non-backpackers, wearing climate appropriate clothing is important. Currently, I am thinking of the folks in my hometown of Western New York that were hit with a major snowstorm. Those people that spent days digging out from under six-feet of snow were thankful for having the right layers.

Though cotton may seem like a "greener" choice is selecting outdoor clothing, there are more environmentally friendly selections also boast better performance. Some of my favorite year-around baselayers are merino wool and cocona. Cocona is made from the carbon produced from discarded coconut shells - it is comfortable and performs well in all conditions. Within the synthetic market, manufacturers like Patagonia and Rab use recycled materials to produce their garments. Plus, despite its image, the general production of cotton is far from green with its immense use of pesticides and irrigation. According to an article in The Triple Helix, cotton crops account for nearly 25% of all the pesticides that the world uses. Hence the push for "organic" cotton from the environmentally conscious crowd. I do my best to think of the environment when I shop.

Thanks again, everyone for your great and thoughtful comments.

Ana Koulouris on November 23, 2014:

Not only is this a well-written article, it is very informative and interesting. While I'm not much of an outdoors-woman, the information you present can be useful during shorter outings into nature, not solely hiking and backpacking trips. Well done, Dan!

Michael O'Connor on November 23, 2014:

I find this to be just the opposite. When I wear synthetic materials I sweat twice as much and the shirts stay damp. while when wearing cotton it breaths and dries faster. I have been camping in snow at -10 to 0 degrees wearing only cotton and have stayed dry and warm. yet I have been camping in dry weather at 30 to 40 degrees wearing synthetics and was wet and miserably cold

Ed Palumbo from Tualatin, OR on November 22, 2014:

My ancestors wore animal skins for millenia, but better options have been developed. There's a place for wool, for goose down, for Gore-Tex, and certainly for synthetics. Man did wear cotton for millenia, usually in temperate or warm climates. Those who relied on it in cold, wett conditions did so at their peril. Should you find yourself in subfreezing weather and eschew every modern improvement in extreme cold weather wear, your hypothermic experience may change your opinion. The objective is to survive, to operate comfortably in challenging conditions...depending on where you live, that may mean compromising your environmental ethic to survive the threat of the environment in which you find yourself. Things to ponder.