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What is Considered High Altitude for Hiking?

What is Considered High Altitude for Hiking?

Summiting your first peak is a rewarding experience, no matter how high the altitude may be. Still, once you’ve worked your way up to 14ers and beyond, things start to change a little bit. While you should always do your research when hiking on remote trails, adding elevation gain to the equation ramps up the necessity for a knowledge base of not only the area but also how to hike at high altitudes safely. 

What is considered high altitude for hiking? Anything above 8,000 feet is considered to be a high altitude. Air pressure decreases the higher we climb, and with less air pressure, our bodies can’t take in as much oxygen. Some hikers are affected as low as 7,000 feet, and every 1,000 feet you climb, there is about 3% less oxygen available. For example, at 10,000 feet of elevation, your body only takes in about 2/3 (65%) the amount of oxygen it would at sea level. 

Beyond knowing what defines a high altitude hike, it can be helpful to identify steps to take to prepare for one. Being prepared before you go and knowing what to do if a hiking partner gets altitude sickness gives you the tools you need for a safe and successful adventure. 

High altitude hiking and altitude sickness

Luckily, deaths due to high-altitude sickness are relatively uncommon. However, there has been an increased interest in travel to high-altitude areas in recent years. This peak in interest may result in more frequent instances of altitude-related illnesses. Acute Mountain Sickness (AMS) is not a fatal condition, but other types of altitude sickness can prove to be fatal within hours or days if left undiagnosed and untreated. 

Honestly, the biggest hurdle for a lot of hikers is accepting that they should turn around when they get sick, especially if they’re close to the summit. However, knowing the signs and symptoms of different altitude sicknesses and accepting when you are sick could potentially save your life. 

Here are some of the most common types of altitude sicknesses

  • Acute Mountain Sickness (AMS): The most common type of altitude sickness is also the least severe. Symptoms will last anywhere from 8-36 hours after the ascent. However, if left untreated, it can lead to more severe illness. Symptoms include headache, nausea, vomiting, dizziness, fatigue, loss of appetite, and difficulty sleeping. 
  • High Altitude Cerebral Edema (HACE): Can be considered an extreme form of AMS. Symptoms are difficult to identify and will often appear at night. Low oxygen injury will affect the brain and impact general thought processes. Usually, a travel companion will notice symptoms as they become more severe. Symptoms include worsening headache, more frequent vomiting, exhaustion, confusion, staggering when walking, abnormal behavior, hallucinations, inability to think clearly, and a coma (in severe cases).
  • High Altitude Pulmonary Edema (HAPE): This illness will appear with or without symptoms of AMS. It is essentially the lungs’ response to high altitude. The low level of oxygen can cause blood vessels in your lungs to tighten, making pressure in your lungs arteries higher. This reaction causes fluid to leak from blood vessels into your lungs. Symptoms commonly appear at night when resting and then worsen with exertion the next day. Symptoms include extreme fatigue, chest tightness, shortness of breath (even when resting), coughing (may produce pink, frothy fluid), rattling or gurgling when breathing, slight fever, and blue/gray fingernails or lips. 
  • High Altitude Retinal Hemorrhage: Usually, not a noticeable impact unless the macula of the eye is involved. Blurred vision will occur or loss of sight if severe. 

Knowing the types of altitude sicknesses, there are is extremely helpful. On one of my backpacking trips in South America, there were numerous mountain passes and varying elevations almost daily. At the time, I was not extremely aware of altitude sickness, but luckily my hiking partner was a medical student.

She was able to recognize her symptoms of AMS before I was. Fortunately, we were able to get to a town of lower elevation in time for her to recover without her sickness worsening to become HACE. 

Although that experience was scary, it taught me a lot. Since then, I have invested more time and energy in learning backcountry medicine and am always on the watch for my hiking partners’ safety as well as mine. 

Many hikers, especially on their first high altitude journeys, don’t know all of the symptoms. Plus, symptoms can worsen even days after your summit. Knowing when to call it and turn back to seek medical attention can help prevent AMS from taking a turn for the worst and potentially becoming fatal. 

Other Risks of High Altitude Hiking

Other than altitude sickness, there are a few other health risks to be aware of and in tune with when traveling at a high altitude. These risks include: 

  • Dehydration: On average, we exhale up to 6 liters of water per day. Staying hydrated can be hard to remember, especially in colder temperatures. Have designated times to drink water and monitor everyone’s intake. 
  • Hypothermia: This is only an issue in cold weather situations. Be aware of the signs and symptoms of hypothermia as well as treatment if you are mountaineering or climbing in cold weather. 
  • Frostbite: Another cold-weather possibility and dehydration can make frostbite worse. 
  • Snow Blindness / Severe Sunburn: Although it gets colder as we climb higher, the UV rays will increase too. Having proper protective sun gear, like goggles, can prevent this. 


How to Prevent Altitude Sickness

Beyond knowing how to recognize altitude sickness in its many forms, prevention can stop you from experiencing it all together. I will go through some of the most recommended and effective preventative measures to take to prevent altitude sickness when hiking above 8,000 feet. 


Giving your body proper time to acclimate to the elevation difference is one of the most important things you can do to prevent altitude sickness. When given time to acclimate, most healthy human bodies deal quite well with mild to moderate hypoxia, which is a localized deprivation of oxygen in the body. 

Having at least 3-5 days of acclimatization to high elevation areas can give your body time to adjust to the new level of oxygen available in the air. Usually, people choose to acclimate when hiking or climbing at 10,000 feet or above. This means that acclimatization should take place at elevations between 8-9,000 feet. 

Travelers become more prone to altitude sickness when they do not adequately acclimate their bodies to the new environment. This is true for elevations of 8,000 feet as well. 

Within the topic of acclimatization, I will add that having a gradual ascent can also prevent some altitude sickness. The term gradual ascent, when used in regards to preventing AMS and HACE, refers to slowly increasing the sleep elevation. The elevation at which you sleep tends to be more influential than that of the elevation during hiking hours. In general, you do not want to gain more than 1,000 feet of sleeping altitude per day. Follow the golden rule of “climb high sleep low.”

Proper Nutrition

A significant part of acclimating your body is giving it the proper tools to do so, and this comes down to nutrition and hydration. These will be essential factors when you are ascending as well. 

Some food groups and nutrients to target and eat at high altitude include: 

  • Carbohydrates: These should come from whole grains and things like dates, bananas, and sweet potatoes. Avoid eating sugary foods and refined carbohydrates. For most people, high altitude increases your body’s use for carbohydrates, so they become an even more valuable fuel source
  • Antioxidants: Keep your immune system running smoothly by eating foods high in antioxidants. These will usually be fruits and vegetables, so you may need some freeze-dried or dried meal options. 
  • Iron: With less oxygen available, your body starts to produce more red blood cells to help transport the oxygen you have. Iron is a crucial player in this process. You can eat leafy greens, tofu, dried fruit, lentils, oatmeal, and beans as an easy way to keep your iron levels up. 
  • Potassium: Your body tends to use a lot of potassium at high-altitude, especially in the first few days. Eating foods high in potassium will help replenish your supply and re-balance your plasma electrolytes

Ensuring that your body is getting the proper vitamins and minerals can be hard when you are in a remote high-altitude location. You may want to consider bringing supplements along to boost your levels of things like iron or potassium. 

Here are a few things to avoid consuming at high altitude: 

  • High amounts of caffeine
  • Alcohol 
  • High-fat foods

High altitude is no place for a diet, so don’t skip meals! Sometimes altitude can lessen your appetite slightly, but you should still eat. Your body’s working overtime up there, so give it some fuel.

What to Do When Symptoms Appear

If you or your travel partner experience altitude sickness of any kind, it is important that you know what to do. Maybe most importantly is that altitude sickness of any severity needs to be acknowledged. The allure of the summit may try to convince you that you can sleep it off and continue the next day, but the more likely scenario is that your symptoms will worsen. 

For AMS, HACE, and HAPE, the first thing to do is to descend immediately. Usually, 500-1,000 meters (1,600-3,300 feet) is sufficient. If symptoms do not improve within 12-24 hours of initial descent, descend further, at least to the last sleeping altitude where symptoms were not present. 

The next best thing is to rest and hydrate. For cases of HAPE and HACE, medical attention will be required. In most cases, oxygen will need to be administered along with some medication to bring symptoms down. 

Ibuprofen or other Analgesic drugs like aspirin can be used for symptomatic treatment. However, the most important thing to do is to begin to descend. Your body needs to return to a lower altitude with less air pressure and more oxygen to recover. 

Aconcagua Mountain

Be Prepared When Hiking at Altitude

Whether you are tackling your first 14er or preparing for a mountaineering course, breaking into the world of high altitude exploration is rewarding and challenging. Knowing what to expect can be difficult, and everyone’s bodies react differently to high altitude situations. One thing for certain is that if you recognize symptoms of any form of altitude sickness, it’s time to head down. 

The more time you spend in high altitude, the better you will be at gauging your limits. Be an advocate for your health and those around you out there.


What elevation do you need oxygen while hiking?

For most people, it is common when hiking above 7,000 meters (22,965 feet). Almost everyone will need to use oxygen when hiking above 8,000 meters (26,246 feet). For a reference, Mount Everest is 8,848 meters (29,029 feet), and after 8,000 meters is known as the death zone. There have been some mountaineers that successfully climbed Everest without supplemental oxygen, but it is infrequent and hazardous to do so. 

How much water should I drink at high altitude?

The Institute for Altitude Medicine recommends drinking 3 to 4 liters of water per day. This will be about 1-1.5 liters more than usual. At high altitudes, your body loses water through respiration almost twice as fast as it does at sea level. Supplementing water with electrolytes is a good idea as well. 

(Statistics in this article are from the CDC Handbook on Environmental Hazards and Non-Infectious Health Risks)


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