Acute Mountain Sickness (AMS)

Altitude Sickness is termed as “Acute Mountain Sickness” which occurs when the body does not adjust due to the decreasing the amount of oxygen available on high altitude as we climb higher ranging usually about 2500 meters. Generally speaking, Altitude Sickness-Acute Mountain Sickness (AMS) is a medical consideration while trekking in the Himalayas.

Nepal Sanctuary Treks design trekking program carefully and professionally to reduce the effects of altitude sickness. Extensive medical supplies are carried in every trip.

For safety measures on high altitude treks and climbing expeditions, we always carry Portable Altitude Chamber (a life-saving device in case of AMS). All our group leaders/guides are well trained in Wilderness First Aid Course to identify any symptom and take immediate action on the spot. Our guide will provide you daily health checklist, which consists of checking your pulse rate, blood oxygen saturation level, assessing your acclimatization status using the Lake Louise system. Our entire guides are highly proficient in working at altitude and know how to take care of our clients.


Primary symptoms of Altitude Mountain Sickness (AMS)

  • Lack of appetite, nausea
  • Weakness
  •  lightheartedness
  • Insomnia/ Sleep disturbance
  • Pins and needles
  • Shortness of breath upon exertion
  •  Nose bleed
  • Constant rapid pulse
  •  Tiredness
  •  General malaise
  •  Swelling of hands, feet, and face.etc
  • Headache (typically throbbing, often worse for bending over or lying down),

Preventive measures of Acute Mountain Sickness (AMS)

  • To ensure proper acclimatization is waling schedule. This we feel is appropriate to give all the best chance to acclimatize. You can do many things which will aid this process. I.e. walk within a pace that is comfortable for you and allow adequate time for acclimatization (After 3000 meters).
  • Do not climb rapidly or go too far too fast. It is better to climb at a low pace.
  • Avoid consumption of alcohol, sleeping pills, and smoking that dehydrate the body, affect respiration and other metabolic activities result to altitude sickness.
  • Drink a minimum of five liters of fluid per day to retain the normal body conditions. Avoid diuretics (tea/coffee etc).
  • Ascend slowly using small increment and employ the ‘trek high – sleep low’ method. This means climb high during the day and then return back a little to sleep at lower elevations.  This will help you adjust to the altitude.
  • Never trek alone, always take guide/porter and follow the guidance from your group leader and guides.
  • Never leave or descent sick person unaccompanied. And prevent yourself from getting cold.
  • All along the way, you will find warnings about ascending too quickly. If you show signs of altitude sickness, appropriate measures (i.e. descent) must be taken. Inform yourself as much as possible about this issue before you go so that you have an understanding of how it can affect you. As well as inform guide, team leader or others if you feel unease to avoid the problem from getting worse during the trek.
  • Take dark chocolate on high altitude treks. Chewing cocoa considered an aid to prevent altitude sickness in high elevations during the mountain trips.
  • Consume a sufficient amount of carbohydrates like bread, pasta, and potatoes before and throughout your trek which helps to improve energy and performance and minimize the symptom of high altitude sickness.

Treating Acute Altitude Sickness

  • In case of mild symptoms, stay at the same altitude. Ascend only when the symptoms have resolved completely.
  • Descend to a lower altitude immediately in case of serious symptoms.
  • If you have a headache, take ibuprofen or paracetamol
  • Consider Diamox (125 to 250 mg 12-hourly) for 3 days, or for the rest of the time at altitude if symptoms return
  • Consider Stemetil (or other anti-vomiting medication) for continual nausea/vomiting
  • If AMS symptoms are severe, give oxygen (1 to 2 L/min) OR use a pressure bag until symptoms clear
  • Check the victim on a regular basis for signs of HAPE and HACE, especially during the night
  • If symptoms of AMS do not improve or get worse, then descend  to clear symptoms (at least 500m/1640ft


HACE (High Altitude Cerebral Edema)

HACE stands for High Altitude Cerebral Edema. It occurs when fluid collects in the brain. Typically HACE develops when symptoms and signs of AMS become worse and someone who suffers from HAPE may also develop HACE.

The symptoms of HACE (swelling of the brain) usually start one to three days at a high altitude. They include extreme drowsiness, weakness, confusion, irritability, clumsiness, stumbling and have difficulty in walking properly.

Note: Descent to lower altitudes may save those suffering from HACE.

Symptoms and signs

  • Bad headache, which often feels worse on lying down and is not relieved by ibuprofen, paracetamol or aspirin
  • Tiredness, severe tiredness
  • Nausea and or vomiting which may be severe and constant
  • Mental confusion, poor cognitive abilities. The victim requires help with easy tasks such as tying their shoelaces or packing their bag. They cannot do the finger-nose test.
  • Staggering, falling. They cannot do the heel to toe walking test or the standing test
  • Blurred or double vision, seeing haloes around objects
  • Hallucination and lapsing into and out of consciousness
  • Psychotic behavior (aggression, boredom, etc.)
  • Strong risk of being comatose
  • HACE normally takes place at night, and most deaths occur while people sleep instead of descending immediately night or day.

Tests for HACE

  • Heel-to-toe walking test: The victim is asked to take 10 very small steps, placing the heel of one foot to the toes of the other foot as they go. The smooth ground is required and the victim should not accompany while doing this test.
  • Standing test: The victim stand with eyes closed, feet together and arms by their sides
  • Finger-nose test: Ask the victim to close eyes and bring his finger to the tip of the nose.
  • Mental test: This test is applied to assess the level of consciousness. Take into consideration pre-existing verbal and arithmetic skills. It is a decline in ability over time that is significant. The instance of the test includes “Spell name from backward”, ask the birth date, ask about current news, subtract 7 from 100, 7 from 93

Treatment for HACE

  1. Move down immediately (prompt descent will begin to reverse the symptoms). Descend as low as possible; at least 1000m /3280 ft. descend at night or in bad weather if necessary. Carry the victim if possible, as the exertion of walking can create the condition worse.
  2. If there is no way to descend immediately due to various factors like dangerous terrain or weather, not adequate helpers or while waiting for a helicopter then use PAC or Oxygen for one hour and sometimes 4-6 hours of treatment needed. In addition, Inhaling medicine such as Nosia would also help
  3. Give oxygen:
    i) From a bottle using a mask (2 to 4 L/min), OR
    ii) By using a pressure bag (this is roughly the equivalent of 2 to 4 L of oxygen/min)
    NB: If both oxygen and a pressure bag are available, give the oxygen while the bag is being equipped and after the victim comes out of the bag. Never give oxygen inside the bag unless it is designed for this purpose and you have been trained to do so

       4. Give medications:

  • 8 mg of Dexamethasone at once (by mouth, IV or IM) followed by 4 mg 6-hourly. Dexamethasone takes several hours to work. Stop it once below 2500m/8200ft AND after at least 3 days of treatment by tailing off the dose slowly (give the last 3 doses 12-hourly)
  • Treat continual vomiting with anti-vomiting medication
  • Diamox 250 mg 8 to12-hourly

(Note: If you are flying into high altitude straight such as Lhasa or Shyangboche beyond 3000 meters, taking Diamox in advance would be better, otherwise use it when you get mild symptoms of it.)

MEDICINE: Diamox – ½ tab (125 gm) every 12 hours. After using this, you will have mild tingling of hands/feet is common.
Allergy to sulfur based drugs – should not take Diamox. This medicine is meant for Glaucoma – eye disease.

  1. Avoid even the slightest physical exertion if this is possible. Even walking a few steps may make their symptoms worse or reappear. Do not leave the victim unaccompanied
  2. If a person is turning blue or is falling into unconsciousness, provide them rescue breathing before they stop breathing.
  3. Support the victim up in a semi-reclining position as lying down flat may make their condition worse.

HAPE (High Altitude Pulmonary Edema)

HAPE stands for High-altitude pulmonary edema. It occurs when there is an accumulation of fluid in or around the lungs. Symptoms include Short breaths, difficulty walking uphill, the cough that is initially dry but may progress to produce pink, frothy sputum. These symptoms usually start two to four days after arriving at altitude. You may or may not also have symptoms of acute mountain sickness (AMS). HAPE require to be treated immediately. Medication is necessary or descends as soon as possible if you develop symptoms. Waiting to descend can be disastrous and symptoms can worsen quickly.

HAPE Treatment

HAPE can be treated by descending the victim instantly by taking the victim to lower elevation. The victim should be kept warm as well as oxygen and the PAC should be given which is the first step in the treatment of HAPE followed by appropriate medication to relieve symptoms. If it is not possible to descend immediately then the victim should put and zipped in a special inflatable bag called a portable hyperbaric chamber which will give the sense of being at a lower altitude and certain medicine should be given.

Following are some medication used to treat HAPE:

 Nifedipine. This should only be used if bottled oxygen or a pressure chamber is not accessible and the victim is warm and well hydrated. Give the modified release (MR) form of the tablets (20 mg 12-hourly for 2 or 3 days). treat as a shock if victim blood pressure lower down due to Nifedipine (paleness, weak swift pulse, dizziness)

 Diamox 250 mg 8 to 12-hourly

An asthma reliever spray (2 puffs 4-hourly) may help

Test for HAPE

If you feel you need to rest more and more and do not recover your breathing rate at rest even after having rest for 10 minutes then it is HAPE

Who should be careful at high altitudes?

  • People with heart disease/lung successfully treated.
  • Pregnant women
  • Children
  • People with high blood pressure
  • People prone to apnea sleep.
  • People who have had HAPE or OCHA before.
  • Other issues to consider in the mountains are sunburn, temporary blindness caused by snow (ophthalmic) cold and frost.