Why is acclimatization important for human body?

We at The Happy Trekkers have had some trekkers down the line who couldn’t complete their high-altitude treks because of their health issues and had to get down to the base camp or base village reluctantly. We find them struggling to take oxygen, or screaming out of muscle cramps, body pain, nausea, headache, vomiting, etc.

This is an emotional moment for hardcore adventure lovers or travelers because even though they do not want to but they have to give up on their adventure filled treks, unfortunately.

Some of them give it another try even when their body does not permit it which is never recommended and neither do we permit that at The Happy Trekkers, while some prefer to give another chance next time with better preparations.

We have studied this issue for many days, researched about it, discussed it among our team members and noticed that around 20% of our trekkers come unprepared mentally and physically. We keep repeating this to our trekkers before the treks to jog and run everyday for 5kms continuously so as to reach the basic level of fitness.

Even though they are informed about the trek and it’s trails they tend to underestimate its difficulty which then obviously turns into a bad memory. It has also been found in the research that around 8-9% of the trekkers do not acclimate properly when they are going for high-altitude treks.

With a few background checks we got to know that many of them tend to be over-confident and thus they do not keep a day for acclimatization thinking that they are fit enough to cope up with the change in altitude.

With years of experience in mountains we have seen trekkers underestimating the adverse effect of altitude gain and keep pushing their limits even though they know they cannot.

We have discovered that for some trekkers trekking and climbing mountains has become a matter of ego. It's high time that we as a community member should understand the importance of acclimatization and start respecting nature and it's rules.

Let us understand more about altitude and how important acclimatization really is.

What is the effect of high altitude on human body?

Although our body can acclimatize quickly with the change in altitude (except in a few cases) , it is designed in such a way that it can perform its best at sea level. Whenever we shift to higher altitude where the oxygen layer is very thin and keeps decreasing as we go up, we tend to get tired and exhausted quickly while putting in the same effort that we used to put at sea level.

This is because of the presence of lower oxygen which our body is not used to. The biggest challenge that the human body has to face at high altitude is the reduction in the pressure of oxygen that results from a fall in barometric pressure.

Every breath taken at a high altitude delivers less of what working muscles require. Pulse rate and blood pressure go up sharply as our hearts pump harder to get more oxygen to the cells.

In order to cope up with this change in new atmospheric pressure our body has a hormone called erythropoietin (EPO) in the kidney, that triggers the production of red blood cells to deliver more oxygen to the muscles.

EPO actually stimulates the bone marrow to keep producing more and more red blood cells in our body to keep the oxygen supply to a level where the body can function properly.

This is the reason you might have heard that people from sea level taking flight to Leh have problems like vomiting, dizziness, breathing problems after landing at the airport.

If you are also planning to take a flight to Leh, make sure to go under a preventive course of Diamox 24 hours before your flight and drink plenty of water to avoid getting dehydrated.

Acclimatization can prevent all future problems like HAPE and HACE.

The best and effective way to get your body acclimatized to the new environment is by giving it the time to do so. Often people who are new in mountains think that keeping one separate day lengthens the itinerary and also adds more cost. But this acclimatization can be very helpful in avoiding future problems like HAPE and HACE.

Wherever you go 10000-11000 feet above sea level, it is very essential to keep one extra day for acclimatization. You might have heard that while trekking or traveling to high altitude, an individual doesn't get proper sleep, has headache, or muscle pain or breathing problem, this is because he/she has been hit by Altitude Mountain Sickness or AMS.

This is something serious and should not be ignored under any circumstances. This is the reason it is generally advised to climb at higher altitude and get down to a lower altitude to sleep, this helps the body to acclimatize in the new environment.

The most adverse and advanced stage of AMS is HAPE or HACE.

They stand for -

HAPE - High Altitude Pulmonary Edema

HACE - High Altitude Cerebral Edema

So what is HAPE and HACE? Let me give you a short information on both of these.

High Altitude Pulmonary Edema (HAPE) - This is a severe form of altitude sickness which happens if the initial stage that is AMS is ignored and an individual keeps on gaining altitude furthermore without giving proper acclimatization time to the body.

Along with other illnesses related to altitude, HAPE occurs above 2500 meters but can occur at altitudes as low as 2000 meters. The worst thing about HAPE is that it escalates very quickly.

What generally happens is that the lungs in the human body get filled up with extravascular fluid, and the individual gets the feeling of drowning. You feel very fatigued and weak, you cannot sleep properly and may feel like you are suffocating. Whatever you do, you will get tired easily.

The recommended treatment is descent to a lower altitude as quickly as possible, with symptomatic improvement seen in as few as 500 to 1,000 meters. However, descent is not mandatory in people with mild HAPE and treatment with warming techniques, rest, and supplemental oxygen can improve symptoms.

High Altitude Cerebral Edema (HACE) - In this form of sickness the brain swells with fluid because of the physiological effects of traveling to a high altitude. It generally appears in patients who have acute mountain sickness and involves disorientation, lethargy, and nausea among other symptoms. It occurs when the body fails to acclimatize while ascending to a high altitude.

The main clinical signs of HACE are confusion, confusion, changes in behavior, difficulty speaking, vomiting, hallucinations, fatigue, ataxia, headache, blindness, paralysis of a limb, unconsciousness, total paralysis, and in the final stage, coma.

If an individual is diagnosed with any of these symptoms, he/she should be immediately given a oxygen cylinder until the oxygen level goes up to at least 88-90. The individual has to be brought down then and there with a guide or two who are well aware of the condition of the trekker. The evacuation process also includes giving a dexamethasone orally 8gm.

So what medicines should you carry next time whenever you plan for a high-altitude trek?

So whenever you are planning for your trek, make sure you carry the basic medical kit with you. I will be dividing the medicines into three parts -


  1. Crocin / Paracetamol / Calpol 650 - For fever or high fever

  2. Zintac / Rantac / Omez - For Acidity problems

  3. Cough Syrup - For coughs

  4. Vomistop / Avomine - For avoiding motion sickness or vomiting (Try not to use at High-Altitude, can be symptoms of AMS.

  5. Spasmonil - For Abdominal cramps

  6. Strepsils - For sore throat

  7. Mosquito Repellent - To prevent against mosquitoes or insects bite

  8. Other Allergic Medicines - If you have specific Allergies

  9. Betadine Soultion - To clean the wounds

  10. Waterproof Band-aids - To prevent cuts

  11. Cotton and Antibiotic Ointments - For cleaning and wounds

  12. Sanitary Pads or Menstrual Cups - For menstruating womens. (We suggest our trekkers to use menstrual cups, because these can be reused and hence less waste generation. Even if you are using Sanitary Pads make sure to carry it back along with you, and dispose it off properly when you are at the base.)


  1. Digene - For indigestion

  2. Eno - For gas, acidity

  3. ORS - For dehydration

  4. Norflox TZ - For loose motion or amoebic infection

High - Altitude

  1. Diamox - To prevent symptoms of AMS. 125gm - 500gm a day, depending on severity, every 12 hours until you return to the base camp.

  2. Nifidipine - To prevent symptoms of HAPE. 4mg to 8mg depending on severity. Immediately DESCEND and do not CLIMB further.

  3. Dexamethasone - To prevent symptoms of HACE. 4mg to 8mg depending on severity. Immediately descend and do not CLIMB further.

What are you waiting for, pack your bags and head on to the most awaited trek you wanted to do. Happy Trekking ;)


Recent Posts

See All