Planning to go on a high altitude exposure hikes in Nepal, India or other places? All these adventures comes with a high risk of mountain sickness, it’s always good to have some knowledge about AMS, Symptoms and prevention before you start for the hike and be well prepared.

ACUTE MOUNTAIN SICKNESS (AMS): Acute mountain sickness (AMS) is the effect on the body of being in a high altitude environment. AMS is common at high altitude that is above 8,000 feet (2,440 meters). Generally happens when our body fails to acclimatize to the decreasing amount of oxygen available on high altitude as we ascend higher. AMS is caused by going up high too fast and can be fatal if all the warning signals are ignored. Note that it is not the actual altitude, but the speed at which you reach higher altitudes which causes the problems.

Altitude illnesses are generally described in these 3 ways, the last two of which can turn fatal:

  • ACUTE MOUNTAIN SICKNESS (AMS) is the mildest, most common version.
  • HIGH-ALTITUDE CEREBRAL EDEMA (HACE) is when the brain begins to swell.
  • HIGH-ALTITUDE PULMONARY EDEMA (HAPE) is when the lungs begin to fill with fluid.

ACUTE MOUNTAIN SICKNESS (AMS) is a condition caused by rapid ascents to high altitudes and the altitude sickness increases for most people at around 3,000m above sea level and some can experience altitude illness symptoms even lower elevation and there is no correlation between age, fitness level, health conditions, gender and experiences of going to high altitude as climbing more than 500m a day then there is probability of altitude illness.

HIGH-ALTITUDE CEREBRAL EDEMA (HACE) is a severe altitude sickness condition and occurs when pressure build-up in the brain results in fluid breaching the capillary walls in the cranium and it is a rare condition on general treks, but much more common among mountaineers in high altitude mountain ranges such as the Himalayas.

HIGH-ALTITUDE PULMONARY EDEMA (HAPE) is another fatal altitude illness condition and occurs when fluid breaches the pulmonary capillaries and enters the lungs. Fluid in the lungs inhibits the effective exchange of oxygen to the blood.

Consult a medical professional to know in more detailed on high altitude sickness. This article offers a general overview of altitude illnesses:

  • Causes
  • Symptoms and treatments
  • Prevention


Acute mountain sickness is caused by reduced air pressure and lower oxygen levels at high altitudes.The faster you climb to a high altitude, the more likely you will get acute mountain sickness.

You are at higher risk for acute mountain sickness if:

  • You live at or near sea level and travel to a high altitude.
  • You have had the illness before.
  • You ascend quickly.
  • You have not acclimatized to the altitude.
  • Alcohol or other substances have interfered with acclimatization.
  • You have medical problems involving the heart, nervous system, or lungs.


ACUTE MOUNTAIN SICKNESS (AMS) is the mildest form and it’s very common. The symptoms can feel like a hangover – dizziness, headache, muscle aches, nausea.

HIGH ALTITUDE PULMONARY EDEMA (HAPE) is a buildup of fluid in the lungs that can be very dangerous and even life threatening.

 (HACE) is the most severe form of altitude sickness and happens when there’s fluid in the brain. It’s life threatening and you need to seek medical attention right away.

Symptoms you might have:

  • Headache
  • Dizziness
  • Nausea
  • Vomiting
  • Fatigue and loss of energy
  • Shortness of breath
  • Problems with sleep
  • Less appetite

Symptoms usually come on within 12 to 24 hours of reaching a higher elevation and then get better within a day or two as your body adjusts to the change in altitude.

If you have a more moderate case of altitude sickness, your symptoms might feel more intense and not improve with over-the-counter medications. Instead of feeling better as time goes on, you’ll start to feel worse. You’ll have more shortness of breath and fatigue.

You may also have:

  • Loss of coordination and trouble walking
  • A severe headache that doesn’t get better with medication
  • A tightening in your chest

If you develop a severe form of altitude sickness like HAPE or HACE, you might have:

  • Confusion
  • Shortness of breath even at restACUTE MOUNTAIN SICKNESS
  • Inability to walk
  • A cough that produces a white or pink frothy substance
  • Coma

AMS TREATMENT: The good news is that the body can cure this by itself. You have to give it sufficient time, though, to adapt to a higher altitude. Descend to the last elevation you slept at without feeling symptoms. Then rest until you feel better.

HACE TREATMENT: A person diagnosed with HACE needs to immediately be escorted to a lower altitude. Full resolution of symptoms simply from descending is unlikely, so you should be thinking about how to contact medical help as soon as HACE is suspected.

HAPE TREATMENT: To prevent added stress on the lungs, a HAPE sufferer should be carried to a lower elevation immediately. Left untreated, HAPE can cause someone to collapse and die. Call a medical professional if symptoms persist.


The best way to prevent altitude sickness is to travel to altitudes above 3,000m slowly.

It usually takes a few days for the body to get used to a change in altitude.

ACCLIMATIZATION is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), allowing it to maintain performance across a range of environmental conditions.

You should also:

  • avoid flying directly to areas of high altitude, if possible
  • take 2-3 days to get used to high altitudes before going above 3,000m
  • avoid climbing more than 300-500m a day
  • have a rest day every 600-900m you go up, or every 3-4 days
  • make sure you’re drinking enough water
  • avoid alcohol
  • avoid strenuous exercise for the first 24 hours
  • eat a light but high calorie diet
  • avoid smoking


It’s hard to predict exactly how your body will react to high altitudes because everyone is different. Your best defense against altitude sickness is not to climb too high too fast and to be prepared by practicing the tips above.

If you have any existing medical conditions, like heart problems, trouble breathing, or diabetes, you should talk to your doctor before traveling to high altitude. These conditions may lead to additional complications if you get altitude sickness. Always listen to your body and Hike Safely.

Getting to the top is optional. Getting down is mandatory.” ― Ed Viesturs,

No Shortcuts to the Top: Climbing the World’s 14 Highest Peaks.

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