Acute Mountain Sickness

Acute Mountain Sickness

Mountain climbing and trekking in Nepal is a thrilling experience that every adventurous person wants to try at least once in their life. But it is no easy affair and climbers are faced with a number of obstacles- either personal or natural. One of such problems that hinders an easy climb is –AMS which is also known as acute mountain sickness, hypobaropathy, altitude illness or soroche.

Altitude sickness is a pathological effect of high altitude on humans due to exposure to the low partial pressure of oxygen at high altitudes. It usually occurs above 2400 m (8000 ft) and might range from mild headaches and tiredness to life threatening conditions. It depends more on the speed of ascending (rate of climbing) than the altitude itself so it is hard to determine the effect of altitude sickness on the basis of age, sex, health condition and other such factors. As more people are elevating to higher altitudes for more recreational activities like skiing, mountain climbing, etc., altitude sickness is a common problem with large number of people like 1/3 rd of Colorado mountain skiers and almost half of people who travel to the Khumbu region of Nepal famous for its Everest Base Camp Trekking . It can be of different types based on altitude level or the degree of effect on the victim.

High altitude/ acute sickness: It occurs at 3000m and higher and is the mildest form that does not affect physical activity, but only causes nausea, dizziness, loss of appetite, etc.

Very high/moderate altitude sickness: When there is problem in coordination and ineffectiveness of medicine t symptoms of acute sickness, it is moderate sickness which occurs at more than 5000m. If a person cannot walk straight, evacuation of descent is a must.

Extremely high/severe altitude Sickness: At altitudes of more than 6000m, the symptoms worsen with fluid buildup, disturbance in physical performance, fainting, or even coma and require immediate descent to lower altitudes and medical attention.

Symptoms of Acute Mountain Sickness

Some symptoms of altitude sickness can appear as soon as ascent whereas some appear after a few hours of ascent to highest altitudes. The signs also differ according to the health of the people and their susceptibility. Headache is the most basic and common symptom paired with the following:

  • Lethargy
  • Lack of performance
  • Lack of coordination
  • Lack of appetite
  • Insomnia
  • Nausea
  • Nosebleed
  • Swelling of hands, feet and face
  • Drowsiness and excessive flatulation .

Once the primary symptoms appear, preventive measures should be taken otherwise the sickness may turn severe with the following symptoms.

  • Breathlessness
  • Heart palpitation
  • Blue tinged skin and nails
  • Frequent coughing with frothy or bloody sputum
  • Irrational behavior and depression
  • Inability to walk properly in a straight liner.


Complications of Acute Mountain Sickness:

If the signs and symptoms are not noticed or treated properly and in time, it could lead to very serious and fatal conditions. The complications that could arise from altitude sickness are as follows:

HAPE : High altitude pulmonary edema is the accumulation of fluid In the lungs of the casualty when the body tries to correct the breathing rate as well as dehydration by releasing water from the organs (lungs in this case). It can be treated by descending to lower altitudes.

HACE: It is the accumulation of blood in the brain when the brain tries too hard to adjust to the lowering oxygen level. First the casualty has problems walking and coordinating movements, then lethargy and coma might occur finally leading to death if not cured in time. Dexamethasone can provide relief and descend is the only cure for this sickness.


The percentage of oxygen in the atmosphere at the sea level is 21%, which remains constant up to a certain height. This is required to maintain proper mental and physical balance. As altitude increases, the oxygen molecules per breath as well as the barometric pressure decreases. In such case, the body needs to make adjustments to the low oxygen level, which causes the imbalance resulting in nausea, weakness, insomnia etc.

The low pressure at high altitude also causes the leaking of fluids from the lungs and brain capillaries which leads to fluid build-up. This could lead to altitude sickness or even severe problems.

At higher altitudes, the rate of loss of water from the body is high i.e. dehydration occurs. This could also cause symptoms of altitude sickness.

Rapid ascent, amount of physical activities as well as individual susceptibility could cause altitude sickness.


TREATMENT of Acute Mountain Sickness

Once the symptoms are severe, it is important to treat altitude sickness immediately as it could turn fatal. The best and most reliable treatment is descent, which provides the amount of oxygen and air pressure that the body needs to stabilize. If descent is not possible, then other treatment methods include:

  1. In case of mild sickness, medicines like dexamethasone and acetazolamide can be taken which work as painkillers to reduce the severity of the symptoms. Dexamethasone is a more effective drug as it helps to lessen the effects of HACO, lethargy or people in comas in high altitudes.
  2. Ibuprofen, Nifedipine, Frusemide, etc are other drugs that can be used to cure altitude sickness.
  3. The Gamow bag (a portable sealed chamber with a pump to fill it with oxygen) is another treatment that helps in the acclimatization process in case of altitude sickness. Once the casualty is placed inside the bag, they regain stability within 10 minutes due to the atmosphere that corresponds to the altitude of 900-1500 meters and gives enough time to descend or acclimate.
  4. In the absence of Gamow Bag, oxygen can be provided by the physicians at the Base camps or resorts to help reduce the effects of mild or moderate sickness without descent.
  5. Steroids can be used to treat pulmonary or cerebral edema temporarily.



  1. Acetazolamide (Diamox) is the best preventive measure as it speeds acclimatization.
  1. Avoid physical exertion for the first 24 hours.
  1. Avoid consumption of alcohol and sleeping pills as they cause dehydration and dizziness.
  1. Drink plenty of fluid and consume high carbohydrate diet.
  1. However the best prevention would be to ascent at a slow rate and give the body enough time to acclimate. The sleeping altitude is maintained low (not increased by more than 300 meters) i.e. climbers climb higher during the day and return to a lower altitude to hasten the acclimatization process. This approach is also called “climb-high, sleep-low” and helps the body adjust to decreasing oxygen level by producing more red blood cells. If travelling via aircrafts, people can acclimate by stopping at an intermediate altitude.


Things to remember

  • Be clear regarding the limitations on physical activities, rate of ascent, altitude attained, use of additional oxygen, immediate descent, etc during the trip.
  • Avoid alcohol, tobacco and sleeping pills.
  • Only use prescribed drugs with exact dosage.
  • Carry all preventive measures like drugs, Gamow bag, oxygen tanks etc.
  • Do not ignore signs and symptoms, no matter how mild they are.
  • Do not hesitate to stop the climb or descend in case of physical difficulties.
  • Take immediate actions in case of symptoms of HAPE or HACE appear.
  • Continue routine checkups even after the cure of altitude sickness.