High Altitude Travel: Heat and Cold-Related Illnesses and Injuries

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High altitude travel may face you not only with the dangers of altitude illness but also with various heat and cold-related illnesses and injuries. Trekking and travel through places with high altitude brings changing weather conditions and environments from extreme cold, snowy and windy heights to extreme heat as both can happen on the same trek. Thus you need to be properly prepared for the dangers of mountainous regions and high altitude to make your travel safer and more enjoyable.

This blog post is aimed at making you familiar with some of the most widespread and dangerous heat and cold-related illnesses and injuries, their signs and symptoms, prevention as well as proper field treatment.

Two persons alpine climb

High altitude travel can lead to both heat and cold-related illnesses and injuries

Heat and UV radiation-related illnesses and injuries

You know that intense ultraviolet radiation (UV) from the sun is dangerous, however, you probably don’t know that UV radiation increases up to about 20% for every 1000m above the sea. Thus, everyone who hikes at altitude is exposed to more UV radiation and as a consequence to burn injuries from overexposure to UV radiation. Moreover, when reflected off snow and ice, UV radiation is even more serious threat to unprepared people in the mountain.

There are various potentially dangerous heat-related illnesses and injuries as some of them are also typical of summer hiking. The main cause for these conditions is the heat that builds up by extreme exertion or by exposure to hot conditions. Often this heat cannot be released through the skin because high humidity slows evaporation and impairs heat dissipation. There are two major kinds of heat illness – heat exhaustion and heat stroke as the former is milder compared to the latter.

Table 1: Environmentally related conditions and injuries associated with high altitude travel

Environmentally related dangers of hiking at altitude

Source: Mountaineering: The Freedom of the Hills*

Heat exhaustion

Heat exhaustion is a heat-related illness that affects mainly the elderly, dehydrated or salt-depleted individuals, people who aren’t acclimatized to hot climate, and people who cannot sweat properly like those taking medications that interfere with the skin’s ability to release heat through producing moisture. The main symptoms of heat exhaustion include headache, faintness, lassitude, thirst, dizziness, nausea, vomiting, rapid pulse and heart rate, and cool and clammy skin. The reason for these symptoms is the inadequate blood supply to the brain and other vital organs caused by the shunting of blood to the skin.

Prevention of heat exhaustion

Prevention includes proper hydration (rest in the shade during the hottest part of the day), acclimatization (usually takes around a week), wearing light-colored clothing and covering the head, and soaking hats and clothes in water to cool the body.

Treatment of heat exhaustion

Treatment includes rest (preferably in the shade), proper hydration through drinking plenty of drinks and electrolytes, salt, reduced clothing, and pouring water over the head, body, and clothing to promote cooling.

Heat-Related Illnesses and Injuries: old hikers are prone to heat exhaustion

The elderly individuals are among those most prone to heat exhaustion


Heatstroke, also called sunstroke, is the most serious heat-related illness and a potentially life-threatening condition. It is a failure of the heat regulation process of the body. As a result of exhaustion of the sweat glands, the body core temperature rises to 41°C (106°F) or higher, which causes the victim to feel extremely hot. An ordinary person starts sweating to release the build-up heat through evaporation, however, the skin of an individual with this condition feels hot and dry but does not sweat. What can follow is confusion, deteriorating coordination, delirium or coma. The main and most reliable symptom is an altered mental state, including confusion, incoherent speech, uncooperativeness, irritability, combativeness, and delusions. Some other symptoms of heat stroke include:

  • Headache
  • Weakness
  • Rapid pulse and breathing
  • Flushed, hot skin
  • Loss of coordination
  • Seizures

Treatment of heatstroke

If someone has become a victim of heatstroke, you need to remove the clothing that retains heat and cool them immediately. You can do the following steps:

  1. Immerse the victim in water or ice. Pack them in snow if you’re in the mountain and do not have access to ice or water. Remember that you need to cool them as soon as possible by any means.
  2. Massage the limbs to promote blood circulation.
  3. Cool until the body temperature drops to 39°C.
  4. Monitor the temperature, mental status, and general condition in the next few days. Keep in mind that the temperature may increase again; if this happens, start cooling again.


Sunburn is a skin injury that’s common among hikers and climbers visiting high altitudes. That’s because “thin air, less UV protection“. Moreover, clouds do not filter UV radiation effectively so your skin can burn even on a cloudy day. Furthermore, snow and ice reflect the sun’s rays, which increases the radiative heat transfer.

There are three types of burns depending on the severity of the burn:

  • First-degree burns – superficial; cause redness of the skin; damage tissue but do not kill it.
  • Second-degree burns – cause blisters; kill the upper portion of the skin.
  • Third-degree burns – kill not only the skin but also the underlying tissue.

Prevention of sunburn

The best prevention is provided by covering the exposed areas of the body (skin) with clothing. Clothing filters UV radiation effectively so the skin does not burn. Certainly, not all clothing does the same job as the screening ability of garments depends on the weave. Though tight weave is hotter to wear, it protects better against UV radiation. Lightweight hiking clothes with UPF rating are specially developed to protect from the sun’s ultraviolet rays. Sunscreen products also work well, especially when properly applied.

Treatment of sunburn

Sunburn is like any other burn so there is no need for special treatment. For milder burns cool the burned area, cover it, and treat it for pain. And… that’s it. For more serious sunburns, you need to wash the area gently with cold water. Then cover it with a sterile dressing. Meanwhile, drink plenty of fluids. You can relieve the pain with antibiotic ointment. Hence, if you have some, use it before covering the burnt skin with a dressing. For serious cases as a result of this heat-related injury, two tablets of aspirin and codeine every six hours may help you relieve pain.

Tents surround boardwalk by mountains

Photo by Ilana Beer

Snow blindness

When the outer layers of the eyes are burned by ultraviolet radiation, the so-called snow blindness occurs. It’s a temporary condition that sets in 6-12 hours after radiation exposure. The first symptoms are dry and light-sensitive eyes that become reddened and teary. This is followed by severe pain in the eyes.

Prevention of snow blindness

There are several methods for the prevention of snow blindness. Sunglasses with UV-protective lenses are indispensable for high altitudes. They will protect your eyes from UV radiation. Polarized layers on the lenses help where reflection is especially intense. If you lose your glasses, you can craft goggles from duct tape or cardboard by cutting horizontal slits for each eye. Sherpas and Tibetans’ favorite method is hair combed over the face.

Treatment of snow blindness

Common treatment of snow blindness includes:

  1. Use drugs that offer pain relief
  2. Cool compresses and darkness also help for pain relief
  3. Cover your eyes with sterile dressings and padding to prevent irritation from eyelid movement

The condition resolves after a day or two, however, sometimes it may take up to a week.

Cold-related illnesses and injuries

Heat and UV radiation-related conditions are among the most prevalent mountain maladies, though cold-related illnesses and injuries probably occur even more often. Cold-related illnesses occur when an individual loses more body heat than the body can restore. The four main mechanisms of the heat loss to the environment are the following: convection, radiation, conduction, and evaporation. See our post about cold weather hiking clothing for more in-depth information about these mechanisms.

Three cold-related illnesses and injuries pose the main threat in the mountains: hypothermia, frostbite, and immersion foot. Hypothermia affects the entire body and can be deadly. Frostbite and immersion foot are localized in their effects but can also have serious consequences.

Hiking at altitude hiker on rugged mountain trail

Photo by JoJo Chuk


As we highlighted in our post about hiking in the rain, hypothermia is a dangerous condition that kills many hikers, travelers, climbers, and others every year. Hypothermia is a potentially deadly condition that occurs when the core body temperature drops to 35°C or less. This temperature drop comes up when the total amount of body heat released exceeds body heat produced. Thus, this cold-related illness can develop and kill at temperatures above freezing.

What causes hypothermia?

It comes as no surprise that hypothermia is often termed exposure. Although many people would suggest that hypothermia comes as a result of exposure to extreme cold, it actually is a result of prolonged exposure to chilly environments often combined with wet clothing and/or exposure to wind. Dehydration, inadequate nutritional intake, high altitude, insufficient clothing, immersion in cold water, and exhaustion are some other factors that can facilitate and accelerate the occurrence of hypothermia. Backpackers practicing high altitude travel must be prepared to prevent hypothermia. Knowing its symptoms and signs can help you recognize them on time so that you may be able to prevent the development of hypothermia. Before continuing with the main symptoms and signs of this cold-related illness, we should note that children and small adults are especially prone to hypothermia. So, be careful when hiking with kids in the mountains.

Interestingly, obese people have an advantage over slim individuals because their fat provides them with better insulation. In addition to the natural insulation provided by your body fat, you can also insulate your body against the cold by using a layered clothing system. It usually consists of a base layer, fleece, and waterproof breathable jacket, however, in very cold weather you’ll have to add some extra layers. Good hiking boots, warm hat, and waterproof gloves add more warmth and serve as another layer of protection. Vapor barrier liners also work very well in less than ideal conditions. They keep the moisture next to the skin and restrict its transmission. This reduces the heat loss, prevents further cooling, and raises the temperature of the body.

Cold-Related Illnesses and Injuries: hypothermia can strike even in sunny and windy weather

Hypothermia can strike even in warm weather if there’s wind and you aren’t properly equipped

Symptoms of hypothermia

The initial symptoms of hypothermia often remain unnoticed or are neglected. They’re the following:

  • Marked shivering
  • Pale skin
  • Fatigue
  • Loss of coordination (stumbling, fumbling hand movements)
  • Lethargy
  • Irritability

The symptoms of severe hypothermia include:

  • Shivering stops
  • Confusion and disorientation
  • Stiff muscles
  • Decreased pulse and respiration
  • Uncoordinated movements
  • Irrational behavior and memory lapses
  • Slurred speech
  • Hallucinations

All these symptoms and signs are followed by the final phase of hypothermia that leads to unconsciousness and death. Keep in mind that the situation can quickly exacerbate and progress from the initial symptoms to the point where the victim cannot perform the functions necessary for survival.

Prevention of hypothermia

To prevent hypothermia you must:

  • Have adequate insulation and avoid being wet
  • Avoid being exposed to the wind
  • Stay well-fed and hydrated
  • Pace yourself to avoid excessive sweating and exhaustion
  • Have a contingency plan in case there are changes in the weather conditions.

Treatment of hypothermia

Mild hypothermia can be treated by stopping further heat loss by applying heat to the victim’s body. Best way to do that is by removing all wet clothing and placing the person in a sleeping bag together with a source of heat – hot water bottles at the chest, under the armpits, and around the groin, warmed rocks wrapped in cloth or a warm person. If the person is conscious, you can give him warm drinks (no alcohol) and later sugar-based foods. Note that rehydration is more important than giving warm drinks.

For cases of severe hypothermia (and generally for people with a body temperature below 31°C), quick evacuation is needed. People with severe hypothermia need gentle rewarming to avoid rewarming shock. Because of the low temperature of such a person, he may show no signs of life and appear dead. Remember the saying “no one is dead until warm and dead” and don’t give up on resuscitation efforts until the person is warm and still shows no signs of life.

Once back to normal temperature, the severe hypothermia patient must be monitored just like someone with heatstroke because temperature-regulating mechanisms may not be stable for a considerable amount of time.

Table 2: Signs/symptoms and treatment of hypothermia

Signs/symptoms and treatment of hypothermia

Source: Evaluation and Treatment of Hypothermia **


Frostbite is the freezing of the blood vessels surrounding tissues of body parts such as fingers, toes, ears, noses, and chins. This cold injury is most common among alpinists (because of the temperature extremes they’re exposed to) and occurs rarely in hikers, though it can happen on high passes and trekking summits where trekkers may encounter low temperatures for long periods of time. As a result of frostbite, blood vessels can be temporarily or permanently damaged. In the early stage blood cells clump in a reversible way, while tissues become cold, painful, and pale.

The first symptoms of frostbite are feeling of “pins and needles” in the affected part; then it will go numb. After prolonged freezing, these clumps may become a permanent problem with serious consequences, especially since the affected individuals don’t feel the affected extremities and forget about the problem. In the later stage, the skin will become mottled blue and then black as tissue death occurs. Frostbite is a dangerous condition that can lead to gangrene and loss of the affected part(s). Keep in mind that frostbitten tissue is damaged and fragile and should not be rubbed or massaged because doing this causes more damage.

Table 3: Severity, treatment, and appearance of frostbite

Frostbite severity table

Source: Treatment of Cold-Induced Injuries ***

Prevention of frostbite

Prevention is a much better option than treatment of frostbite, which is often unsuccessful. The best prevention is through wearing adequate footwear, clothing, gloves and mittens, and equipment. Eating enough food, avoiding dehydration and exhaustion, and experience also helps a lot in preventing frostbites. Avoid constricting boots, skin contact with cold metal, and keep your hands covered and your feet dry. Stop and warm your nose, fingers, and toes while they are still causing tingling and pain before they go numb. Skin-to-skin contact works best for slow warming. Moving your feet, wiggling the toes, and changing your socks at least once a day can help you keep your feet and toes dry and warm. Keep in mind that high altitudes, significant wind, tight boots that restrict blood flow, exhaustion, and a previous history of the problem can increase the potential for frostbites.

Treatment of frostbite

Before giving any treatment, try to assess whether field rewarming is appropriate or desirable. It can be very difficult to identify the degree of frostbite as well as whether the injury is reversible or not. There are four degrees or tiers of injury. Treatment of frostbites in initial stage consists of rapid rewarming of the affected extremity by placing it against a warm area of the body (armpit, hand, stomach, etc.) of the victim or another hiker. When the part restores its color, feeling, and consistency, it can be used given that it is not allowed to freeze again. Be careful, because if that happens, the line of tissue death will probably extend to the refreeze line. So avoid rewarming affected parts of the body if there is a chance of refreezing and direct trauma. Ibuprofen or aspirin can provide temporary pain relief.

A frostbitten foot should be kept frozen until help and safety has been reached because once thawed, it will be impossible to walk on. In the rare case when field rewarming is considered advisable, do it in a water bath with a temperature between 38°C and 42°C. Be very careful and don’t use hot water because the frostbitten part is extremely susceptible to thermal injury. Such a rewarming procedure will probably cause blisters. If still in the wilderness, wash gently, cover with sterile dressings, and leave it alone in order to reduce the risk of infection.

Table 4: Summary of field treatment of frostbite

Frostbite - field treatment

Source: Practice Guidelines for the Prevention and Treatment of Frostbite****


Table 5: What not to do if you discover frostbite

What not to do if you discover frostbite

Source: Mountain & Arctic Survival*****

Immersion Foot

Immersion foot also called trench foot is a cold-related injury to nerves and muscles caused by reduced oxygen distribution. It occurs when a person’s feet have been wet and cool for long periods and affects mainly those who neglect to dry and warm their feet at night, especially after hiking or climbing day after day. Note that to develop this condition (unlike frostbite) the temperature can be well above freezing as it can occur at temperatures as high as 16°C (60°F).

Prevention and main symptoms of immersion foot

The main symptoms and signals are pale, pulseless, cold, tingling, and swollen feet. If untreated, the skin becomes red, hot, broken, blisters develop, followed by bleeding under the skin, and gangrene. Prevention is better than cure so keep your feet dry and out of water. Change your socks regularly. If your feet get wet, take off your boots and replace your socks with dry pair.

Treatment of immersion foot

Treatment includes careful rewarming in a water bath slightly warmer than body temperature (don’t use too warm or hot water because the immersion foot can lead to gangrene). During rewarming, your legs will become reddened and swollen, with bounding pulse because they’re congested with blood. This can be very painful. Elevate the legs to relieve the pain. The recovery period is several days. During that time, avoid walking on feet to avoid tissue damage and to let them recover from this cold-related injury. Keep in mind that the immersion foot may recur.


High altitude hiking can be a very dangerous activity because you are exposed to the elements often without shelter. Thus, you must be acquainted with the dangers that await you when crossing the mountains. Many people, especially beginners, consider that the only dangers up in the mountains are linked to altitude illness and cold-related conditions such as hypothermia or frostbite. However, high altitude travel brings all kinds of environments from extreme cold to extreme heat and everyone who’s interested in treks at high elevations must be familiar with the cold, heat and UV radiation-related conditions, their symptoms, signals, and the dangers they pose as well as prevention and proper treatments. Remember that prevention is better than cure and try to always apply this principle on the trail.


* In R. C. Eng. (Ed.), Mountaineering: The Freedom of the Hills, 8th ed., 2010, The Mountaineers

** Wilderness Medical Society Practice Guidelines for the Out-of-Hospital Evaluation and Treatment of Accidental Hypothermia, WILDERNESS & ENVIRONMENTAL MEDICINE, 25, 425-445 (2014)

*** The Triaging and Treatment of Cold-Induced Injuries, Dtsch Arztebl Int 2015; 112(44): 741-7

**** Wilderness Medical Society Practice Guidelines for the Prevention and Treatment of Frostbite: 2019 Update

***** Davies, Barry, SAS Mountain & Arctic Survival, 1st ed., 2013, Skyhorse Publishing


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