High Altitude Trek in Nepal

What is High Altitude Sickness?

Ram Adhikari
Updated on January 22, 2025

Acute mountain sickness (AMS) is a condition that can arise at altitudes higher than 8,000 feet above sea level. Everyone can get AMS because the atmospheric pressure and oxygen concentration levels decrease. The beginning symptoms of altitude sickness are headache, nausea, dizziness, fatigue, and difficulty sleeping at a new altitude.

In severe cases, it may result in potentially fatal circumstances like HACE and HAPE. HAPE is High Altitude Cerebral Edema, and HAPE is High Altitude Pulmonary Edema. We need emergency medical treatment and evacuation in HAPE and HACE cases. Altitude sickness manifests itself due to the body's inability to adapt to the reduced oxygen environment at high altitudes.

You have to follow a well-planned, acclimatised itinerary and ascent very slowly. Drinking enough water to prevent dehydration, and you have to say no to alcohol and cigarettes. If you get AMS, you can have a medication like acetazolamide (Diamox).

Awareness, precaution, and accurate tracking of symptoms are fundamental for any traveller attempting to go to high altitudes. It will ensure their safety and make their experience enjoyable.

About Acute Mountain Sickness

We all know how dangerous high altitude sickness is. It is said that getting AMS is fine, but dying with AMS is not OK. Everyone has a chance to get AMS while doing high-altitude trekking in Nepal. So we strongly recommend all travellers get information on altitude sickness.

While doing high-altitude treks, there are more chances to get AMS, including the Everest Base Camp Trek. So, everyone who is going on high-altitude treks is at risk of getting AMS because of

  • You leave the comforts of your daily living.
  • Different climatic conditions. 
  • The level of oxygen in the atmosphere is low
  • Your previous medical history might act as a determining factor.
Sign of High Altitude Sickness
HAPE and HACE are the major symptoms of High Altitude Sickness

Acute Mountain Sickness (AMS) or High Altitude Sickness Symptoms 

  • It is a syndrome complex of (a) headache, (b) nausea, (c) dizziness, (d) sleeplessness, and (d) fatigue. Of course, headache is a cardinal symptom.
  • Nobody is immune to AMS above 2500 m.
  • It is not related to physical fitness or gender.
  • Early AMS feels exactly like an alcohol hangover. It is also heralded by a deep inner chill or a sense of not being well.
  • Late or advanced AMS denotes the increase in severity of the symptoms mentioned above.
  • A typical picture will be of a porter arriving at a high altitude carrying a heavy load. Immediately, he enters a corner of the darkroom and rests there, covered with a blanket from head to toe. He doesn’t want any tea or snacks. He starts to throw up once in a while. When asked, he says he has the worst headache, as if somebody is hammering a nail into his forehead, and he feels terrible. He is still huddled in the corner at dinner time. When friends bring him food, he does not even want to look at it. When asked, he says I want to go down.
  • If not infected, AMS could process two fatal complications: (a) High Altitude Cerebral Edema (HACE), meaning swelling of the brain or water in the brain. (b) High Altitude Pulmonary Edema (HAPE), meaning water in the lungs.

HACE (High Altitude Cardio Edema)

It is characterized by increasing headache, vomiting, staggering gait, altered consciousness, and other neurological signs. It is thought to be the progression of AMS. The condition develops more rapidly at night, probably because of a further decrease in nighttime ventilation. This explains the common belief in our people that somebody with a bad headache should not go to sleep.

This is true, but equally important is that they should not remain in the same place either. This fact highlights the importance of keeping a high index of suspicion and making decisions. You must descend after worsening in the day and not wait for the night or the next morning.

The most important test to detect HACE is the tandem gait test. Just let the sick person walk and watch where a person walks straight in a line in a hill-to-toe fashion. If he falls beyond the line, it is strongly suggestive of HACE. The person becomes comatose soon thereafter. 

HAPE (High Altitude Pulmonary Edema)

It is characterized by increasing breathlessness even at rest, a productive cough, and bluish discolouration of lips and tongue. The sputum may become bloodtight later on. It usually strikes the second night onwards. The bluish discolouration is a late sign and should not happen in the hands of good friends.

One crucial thing about HAPE is that it can occur in a setting outside of AMS. People can have full-blown HAPE without headaches and other symptoms of AMS. Thus, when accompanied by the above signs and symptoms of HAPE, they should not be ignored or dismissed in the light of the absence of a headache. HAPE likewise seems to be a completely different pathology

Why does AMS happen?

It happens because of low atmospheric pressure.

A low atmosphere leads to low oxygen tension in the air, which we inhale and causes a series of bodily changes, which may lead to AMS. There is a liking of flute from the bloodstream into the brain. The arteries of the lunges also constrict, causing an increase in pressure, which promotes fluid leakage into the lungs.

These occur when our body does not get sufficient time to adapt to the change in pressure. Some people may be unable to adjust because of abnormalities in their bodies. The absence of one pulmonary, the relative proportion of their brain and the skull, etc.

What are the risk factors for AMS?

  • Rapid ascend is the main risk factor.
  • Dehydration, airway infections, overexertion, sleeping pills, obesity, and alcohol are other risk factors.
  • The previous history of altitude sickness is the best predictor of whether one would be stuck again.
  • Non-flexible itineraries, peer pressure, and tough and stoic personalities are some other risk factors.
  • Excess chill and cold exposure is a known risk factor for HAPE.

What do we do to prevent AMS?

  • AMS is preventable and treatable.
  • Our body is a machine. It always gives signs when it is malfunctioning. All we need to do is listen to our body and help not hinder its process.
  • By slowly ascending, we can digest the altitude called acclimatization. Here, our body gets sufficient time to adjust to the high altitude. It is prudent to take a rest day every third day with the rate of ascending not more than 400 m per day after the altitude of 3000 m. Climbing high and sleeping low is another of the dictums of altitude medicine. Moderate exertion on rest days is also recommended.
  • People who are acclimatizing well will have increased dieresis, which helps prevent fluid from accumulating in the body.
  • Acetazolamide (diamond), a drug, can accelerate the process of acclimatizing. It is taken at a dose of 250 mg twice daily (5 mg/kg for kids).

How do I know where I have AMS?

All ailments at high heights are altitude sicknesses unless proven otherwise. The tendency to rationalize and altitude the initial symptoms of altitude sickness to something else must be avoided and discouraged.

There is a'self-assessment and scoring system ‘called the Lake Louise scoring system to help you know when you have altitude sickness. All should use this to score themselves once in the morning and once in the late afternoon.

Out of 15 points, a score of 3 or more with headaches and other symptoms denotes AMS. The severity is classified as:

3 to 6: mild AMS
7 to 9: moderate AMS
10 or more than 10: severe AMS

High Altitude Trekking in Nepal
Groups are crossing over the Cholo Pass on Everest Trek

What are the treatments for AMS?

  • The million-dollar saying is ‘go down, go down, and go down’.
  • There is no magic altitude at which you should descend. Go down to the place where you were comfortable before. This is usually about 300 m (1000 ft) or more.
  • Stay where you are, and do not ascend if you have moderate AMS.
  • If one is badly stuck, we could only “buy time for him/her to go down by the use of (a) injectable or oral steroid (dexamethasone at the dose of 4 to 8 mg 6 hourly), (b) oxygen, (c) Diamox, (d) pressure bag (Gamow bag), and (e) diuretics (a drug which makes one pee)
  • Nifedipine, a drug used commonly in hypertension, could be used in a setting of HAPE at the dose of 10 mg three to four times per day.
  • Diamox should be avoided by people who are allergic to sulfa drugs. The most common side effects are tingling of the hands and feet and the tongue and lips. Some might experience that the aerated drink tastes flat. Because of the diuretic effect, people may wake up several times in the night.
  • Gastritis is the most common side effect of dexamethasone and can be effectively talked about with the use of drugs like ranitidine.
  • Breathing oxygen reduces the effects of altitude illness.
  • Ibuprofen is also effective at relieving altitude headaches.

The things you have to do to avoid AMS

  • Listen to your body
  • Drink plenty of safe, warm water. (Around 3 litres per day). Dehydration predisposes to altitude sickness.
  • Let the doctor know if you are taking any medicines.
  • Let the doctor know of your previous illness, surgeries, etc. (they might need to prepare the medications accordingly).
  • Stay warm. Take it easy. Light activity during the day is better than sleeping because respiration decreases during sleep, exacerbating the symptoms.
  • Accept your susceptibility to AMS.
  • Be prepared to stay behind or return earlier than the group if you have bad altitude sickness.
  • Understand that you are in an unprivileged situation and things can be less than expected.
  • Eat a high-carbohydrate diet (more than 70% of your calories are from carbohydrates) while at altitude.
  • Leave a trekker behind in your group with someone who doesn’t speak the trekker language.

The things you don't have to do in high altitude

  • Attribute headache, fatigue, etc to cold weather or exertion
  • Over-exert yourself when you first get up to altitude.
  • Take sedatives.
  • Try just to push yourself. The courage displayed on inappropriate occasions is foolishness, not bravery.
  • Be tempted to drink alcohol. (One can drink while coming back, that is, while descending.).
  • Assume that you would be stuck the last.
  • Be very religious and tough. ‘Victory is not reaching the top but coming back safe’.
  • Get frustrated.
  • Present late
  • Take classic baths. (Cold predisposes one to AMS, HAPE)

If you are looking for experienced trekking guides and porters, you can mail Nepal Gateway Trekking,  we have altitude train trekking guides and porters.