Identifying Altitude Sickness – Mountain Climbing Guide

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Mild Altitude Sickness Symptoms: 

  • Headaches
  • Fatigue
  • Lost appetite and nausea
  • Shortness of breath
  • Dizziness
  • Disturbed Sleep

Moderate Altitude Sickness Symptoms: 

  • Awfully bad headaches that can’t be relieved with medication
  • Strong feelings of nausea and muscle weakness
  • Shortness of breath
  • Ataxia (feeling of decreased coordination) 

Severe Altitude Sickness: 

  • An inability to walk
  • Severe shortness of breath
  • Inability to think straight (poor cognitive abilities)
  • Hallucinations
  • Fluid buildup in the lungs

High Altitude Cerebral Edema (HACE): 

High Altitude Cerebral Edema (HACE) is a severe altitude sickness condition. It occurs when pressure build-up in the brain results in fluid breaching the capillary walls in the cranium. It is a rare condition on general treks, but much more common among mountaineers in high altitude mountain ranges such as the Himalayas.

Here are the typical symptoms for suffers of HACE: very bad migraines, loss of coordination, hallucination and disorientation, memory loss, and loss of consciousness (ultimately leading to lapsing into a como). Generally HACE tends to strike at night and the condition can worsen rapidly. Hence, time shouldn’t be lost in getting someone down to lower altitudes if they have suspected HACE. Do not wait for daylight. Descend immediately. 

High Altitude Pulmonary Edema (HAPE)

High Altitude Pulmonary Edema (HAPE) is another fatal altitude illness condition. It occurs when fluid breaches the pulmonary capillaries and enters the lungs. Fluid in the lungs inhibits the effective exchange of oxygen to the blood.

Here are the signs that someone is suffering from HAPE: very tight chest and extreme shortness of breath (even while resting), the feeling of suffocating, particularly during sleep, coughing up white or mucus coloured frothy fluid, extreme fatigue, irrational behaviour and hallucinations.

Like HACE, descent is paramount, but caution should be taken not to exert the person suffering from HAPE as this can worsen the condition. Any available oxygen can and should be administered. The drug, Nifedipine, has also been shown to help ameliorate the condition, but descent is the only 

Altitude sickness daily assessment for guides to check with clients

(Recommended assessment time is 6 hours after gain in altitude)

Suggested ranges for diagnosing Altitude sickness:
3-5 points:
Mild AMS
6-9 points: Moderate AMS
10-12 points: Severe AMS


0—None at all

1—A mild headache

2—Moderate headache

3—Severe headache, incapacitating

Gastrointestinal symptoms

0—Good appetite

1—Poor appetite or nausea

2—Moderate nausea or vomiting

3—Severe nausea and vomiting, incapacitating

Fatigue and/or weakness

0—Not tired or weak

1—Mild fatigue/weakness

2—Moderate fatigue/weakness

3—Severe fatigue/weakness, incapacitating


0—No dizziness/light-headedness

1—Mild dizziness/light-headedness

2—Moderate dizziness/light-headedness

3—Severe dizziness/light-headedness, incapacitating

AMS Clinical Functional Score

Overall, if you had AMS symptoms, how did they affect your activities?

0—Not at all

1—Symptoms present, but did not force any change in activity or itinerary

2—My symptoms forced me to stop the ascent or to go down on my own power

3—Had to be evacuated to a lower altitude

Mild AMS will be common in at least 70% of trekkers and is not a concern unless the symptoms continue to deteriorate. If multiple mild symptoms are present, the guide should keep a good eye on the client to ensure it doesn’t get worse.

Moderate AMS is less common however a good number of clients will still experience these symptoms. The office should be informed as soon as the scoring shows Moderate AMS and a guide should accompany the client and give special attention to as much as possible. Consider pausing or descending if symptoms get worse.

Severe AMS should be handled with extreme care and clients should descend the mountain as quickly as possible to ensure the symptoms do not get worse. Evacuation should be considered.

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