What is Acute Mountain Sickness?

Updated: Dec 4, 2020

Acute Mountain Sickness (AMS) is a condition that every high altitude trekkers should know about. The adventurer who travels to high altitude can at times develop sickness when elevating more than 8000 feet above sea level. It is a negative health effect of high altitude caused by rapid exposure to low oxygen levels.

Why is it caused?

When we go to higher altitudes, the air pressure declines and hence there is less amount of oxygen present in the air. ‘Acute Mountain Sickness’ a.k.a ‘AMS’ is mainly caused because of lower oxygen levels and reduced air pressure in the higher altitudes. The people who reside on higher altitudes elevate their lung capacity because of prolonged rapid breathing that enables them to inhale larger amounts of air per unit of time to compensate for the low oxygen levels compared to the people who reside at sea levels. When a person moves to a place that is located at a higher altitude than the normal sea level, they experience increased breathing rate for a few days before the body gets used to the air pressure and the oxygen level in the air. The problem arises when we travel to a relatively higher altitude than usual. Our body needs some time to acclimatize to the new air pressure and oxygen levels. That is the reason we at “The Happy Trekkers” always keep one day for rest to give our bodies time to accustom to the new weather and conditions before trekking to a moderately higher altitude so that the body can adapt to new changes in the air pressure and oxygen level.

AMS is the result of ascending too quickly, which leaves the body exhausted and due to the lower oxygen level, the body is left deprived of oxygen, which is why we at ‘The Happy Trekkers’ advice our trekkers to take baby steps while ascending and move at a deliberately slower pace than usual.

However, it is to be kept in mind that the amount of time required to acclimatize is different for every individual.

What are the Symptoms of AMS?

There are two types of AMS which trekkers are generally hit by :

  • Mild Acute Mountain Sickness

  • Severe Acute Mountain Sickness

If you have mild AMS, you may face :

  • Dizziness

  • Muscle Aches

  • Rapid heartbeat

  • Swelling of hand and feet

  • Nausea and Vomiting

  • Insomnia

In the case of Severe AMS, you may face :

  • Chest Congestion

  • Coughing

  • Inability to walk

  • Lack of Balance

  • Coughing up Blood

  • Gray or Pale Complexion

What to do when you are hit by AMS in the Mountains?

Generally, whenever you are ascending it is safe to presume any of your sickness to be AMS. Our expert guides and leaders will always be there to rescue you out from the situation and will be monitoring you regularly, a night before the summit and right before the start of the summit. We undertake daily health monitoring when at high altitude to make sure our trekkers can climb as safely as possible, though risk always remains as AMS can develop and worsen quickly.

The best treatment of AMS is to descend quickly to a lower altitude and take rest as much as possible.


In case you are hit by AMS, you might be given a medicine called Acetazolamide (Diamox), widely used by all the trekkers and climbers which helps you to breathe faster than the usual rate. It can help reduce the symptoms. This medicine is diuretic in nature and can make you urinate more often. Make sure you hydrate your body properly before taking this medicine. This medicine works best if taken before reaching a high altitude.

It is generally advised to start with the dosage of the medicine two days prior to the trek (half tablet), and then upon reaching the basecamp it is advised to consume the full tablet every day till the end of the trek.

There are no such side effects of the medicine, apart from the fact that it generates urine from the body at a faster rate, leaving you dehydrated. Thus, make sure to keep your body hydrated before and after taking the medicine.

Who is more prone to hit by AMS?

Acute Mountain Sickness can be tolerable if it is mild, but it can be a serious health threat and can lead to coma if it is severe enough.

There are few points to keep in mind for every trekker or climber to understand who can be prone to the mountain sickness, so as to avoid any such mistakes one must take proper precautions because any individual can develop altitude sickness no matter how fit, young and healthy he/she is.

You can be prone to AMS if :

  • You live at a sea level region and/or near the Sea/Ocean and move to a much higher altitude which you are unaccustomed to.

  • Have heart or lung disease.

  • Have low red blood cell count due to anemia.

  • Past history of Acute Mountain Sickness.

  • Take habit forming medicines like sleeping pills, drugs, narcotics, etc. that lower your breathing rate.

  • Drive to a much higher altitude than normal at an escalated speed.

How to Prevent Altitude Sickness?

Travelers get prone to altitude sickness when they travel to moderately higher altitudes quickly and the body does not get proper time to acclimatize in the new environment which has lower air pressure. Generally, our body has the ability to adjust to new weathers or climates changes but it needs some time to get used to the new environment around it.

Below are the few tips which one should definitely follow in order to avoid getting hit by AMS:

  • Ascend Slowly - Every individual has a different ability and different body type. You might take one day and your partner might take two days to get accustomed to the new altitude. This means in order to absorb more oxygen the body takes time to develop more red blood cells. However that doesn’t always mean that you are more healthy or fit than your partner because the process of acclimatization in response to heat is much faster compared to cold which is much slower. Try to travel not more than 1000 feet each day, and take proper rest at every 3000 feet you climb.

  • Hydrate your body - Drink water regularly while trekking or climbing to higher altitudes. During the extensive climb, the body fluids drain out in the form of sweat and in order to overcome the dehydration you need to continue drinking water, not much at one go but small sips of water after every steep climb.

  • Sleep at a lower altitude - Altitude sickness usually gets worse at night when you’re sleeping. It is always advised to do a higher climb during the day and then return to a lower altitude to sleep, especially if you plan on climbing more than 1,000 feet in one day.

  • Medication - Trekkers across the globe use a medicine named Acetazolamide which is also named as Diamox. This medicine is widely preferred because it increases the breathing rate which helps to take up more oxygen in the body. This medicine has very little side effects as mentioned earlier. It is generally advised to take the medicine two days prior of the trek, followed by taking it every day till the trek ends.

Not to forget that you can still get Altitude Sickness or Acute Mountain Sickness, after taking Diamox. If you start having symptoms of the same, please make sure not to force yourself any further, and get down to the nearest campsite situated at a lower altitude or at the basecamp.

Above all take proper precautions worry less and travel more, Happy Trekking :)


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