Sometimes an unnecessary debate is on between purists and non-purists about acclimatization on a high altitude trek.

The purists feel that using drugs like Diamox to accelerate acclimatization goes against the spirit of trekking. They feel it is better to acclimatize naturally and ascend slowly with breaks – giving the body sufficient time to get used to the higher altitude.

On the other hand the non purists think it is better to be safe than suffer from high altitude sickness. They feel being on a course of Acetazolamide (Diamox) would give them maximum chance of success on a high altitude trek. So they start on a course of Diamox even before they begin their trek.

Now what is the right thing to do? Before I answer this question, a quick background on Acute Mountain Sickness (AMS) would help.

As one climbs above 8,000 feet, the atmospheric pressure starts to fall noticeably. As a result with every breath you take less oxygen reaches your blood. You must work harder to get the oxygen. Your body copes by breathing harder and longer. When you are climbing uphill, this is more acute. Persistent increased breathing builds up carbon dioxide in the blood.

The good news is as you climb higher your body acclimatizes naturally to the decreasing oxygen. Your body builds up a ‘zone of tolerance’ – where it can function normally even with the decreased oxygen. This zone of tolerance moves up as your body acclimatizes to the higher altitudes. However, when the build up of carbon dioxide is beyond your zone of tolerance your body reacts and you fall sick. This is AMS. You get high altitude sickness.

AMS is when along with headache you display the following symptoms:

Video debunking 5 Common Myths About AMS | Altitude Sickness

I find it strange when at 11,000 feet trekkers complain of headache, and others around him say this is normal. It is not. A headache at an altitude is not normal. When you get a headache, drink one liter of water, pop a Disprin and watch for an hour (dehydration is a very common cause of headache). If your headache hasn’t totally disappeared within an hour then you are suffering from AMS. Do not stay at this altitude and begin your descent to the altitude where you last felt comfortable.

This brings me around to the use of Acetazolamide (Diamox) to assist acclimatization and prevent high altitude sickness.

The question is really not whether to use Diamox or not. The deciding factor to guide a trekker should always be the duration and the altitude gain of the trek. If you are doing a 6 day trek and going to high altitude (above 14,000 feet) then your body does not have enough time to acclimatize – even though you may have factored in a rest/acclimatization day. It is best to start on a course of Diamox before you start the trek. If on the other hand you are on a 12-14 days trek, then you have sufficient time to allow your body to acclimatize to the altitude. You don’t need Diamox to help acclimatization.

Generally, you need to allow your body to acclimatize 24-48 hours at an altitude (above 10,000 feet) before going higher. Modern day trekking, unfortunately, does not allow us this time. We usually arrive at a camp at around 2 pm and then have to move to the next higher camp early next morning, giving us less than 16-18 hours to acclimatize. This is usually not enough. Trekkers are prone to AMS under such conditions.

Follow this guide on your trek: if your trek schedule is short and does not allow you more than 24 hours at an altitude, then you are better off being on a course of Diamox.

I often get calls from trekkers telling me that they have been on several high altitude treks and that they have never had to use Diamox. I find this logic baffling. Anyone can get AMS. There is no significant effect of age, gender, physical fitness, or previous altitude experience on AMS. You may get AMS on any trek and it would be terrible if you have to give up on a trek because you did not take this elementary precaution.

90% of the blood’s carbon dioxide exists in a chemical called bicarbonate. This carbon dioxide after travelling through your blood is exhaled by your lungs. Diamox forces the kidneys to excrete bicarbonate from your body (when you urinate).

Your body doesn’t like that. It needs the bicarbonate to exhale carbon dioxide through your lungs.

When Diamox forces you to excrete biocarbonates, your blood, which is used to a certain level of acidity, becomes more acidic. When the blood gets acidic it believes that it has more carbon dioxide in it. So the body gets rid of this excess carbon dioxide in a simple way. It starts to breathe deeper and faster, getting rid of the carbon dioxide, and also taking in more oxygen.

In effect, the increased oxygen speeds up the acclimatisation process. It also greatly reduces you of any symptoms of altitude sickness. Which is why Diamox works best when you start on it a day or two before you get to high altitudes. 

In a recent conversation with Dr Venkatesh Thuppil, the leading expert in India on high altitude hypoxia and the co-inventor of the HAPO bag, he told me that the best step that a trekker could take to prevent any high altitude sickness was to be on a course of Diamox prior to the start of the trek. He said more lives could be saved and more treks successful if the trekkers were on a course of Diamox than without.

Remember, Diamox accelerates acclimatization. It does not cure anything. If you have headache with any of the above symptoms, even after taking Diamox, it means your acclimatization is not complete and you must descend. Under no circumstances should you climb higher if your symptoms still persists.

Start on a dosage of 125 mg every 12 hours 2 days prior to your trek (or when you arrive at Delhi). Increase it to 250 mg every 12 hours from the day you get to the base camp and continue until you complete the trek.

While Diamox is harmless for most people, please check with your doctor whether you are allergic to sulphides. Also check with your doctor if you have high/low blood pressure or diabetes.

Diamox is a sulfa-based drug. So if you’re allergic to sulphides, avoid Diamox.

At Indiahikes, earlier, we used Diamox only in emergencies – however, now we have reviewed our stand and we suggest participants start on Diamox two days before they start the trek. The chances of a successful and stress free trek is much higher if participants start on a course of Diamox on arrival at Delhi.

While Diamox reduces your chances of getting any high altitude sickness, it is important to prepare your lungs to be ready to work with less oxygen. The best way to do that is to prepare for a trek. A good altitude training program must include cardio-vascular, strength and flexibility training. I would recommend a run of half an hour and covering a distance of 4.5 km as good preparatory altitude training.

Here are the benefits of using Acetazolamide (Diamox) to deal with Acute Mountain Sickness (AMS)

How Diamox Deals With Acute Mountain Sickness (AMS)

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Did you know that in a group of 5 trekkers, at least 1 of them shows mild symptoms of Acute Mountain Sickness (AMS)? This is something we’ve noticed a lot over the past decade after leading hundreds of treks in the Himalayas. What we’ve also seen is that in most cases, trekkers don’t recognize their symptoms as AMS and rather attribute it to something else completely. 

AMS could prove dangerous if not caught in the early stages!

Yes, that’s right. If not diagnosed and treated at first, it could quickly climb on to a person mid way through his trek and turn out to be more serious. So in this article, I’m going to talk about 5 of the most common symptoms that you may not recognize as AMS and by the end of the article, you’ll know what signs to look out for, the next time you’re up in the hills. 

To begin with, let me try and tell you what AMS is in brief – Acute Mountain Sickness is your body’s way of telling you that it’s not adjusting well to the high altitudes. Now WebMD and Google will tell you to look out for a headache as it’s the most common symptom of AMS, but it’s important to note that in quite a few cases, people with AMS don’t experience any sort of headache at all. Therefore it becomes critical to recognize the symptoms I’m writing about. 

Always remember the Golden Rule for traveling in the mountains which says about suspecting and treating AMS as your first priority and then moving onto anything else.  

The first and most often ignored sign of AMS that I’ve seen among trekkers is having a bad stomach. A lot of trekkers develop a case of diarrhea wherein they blame their loose motions on the food and water around them. But you shouldn’t do that. Gastrointestinal symptoms are often seen in the milder stages of AMS so it’s essential that you take them as a sign of AMS, treat them, and then continue on with your trek. 

The second sign for AMS that trekkers neglect is nausea. They suffer from feeling like they’re about to vomit any second but wait for actually vomiting before terming it AMS and then treating it. Never make the mistake of delaying. Remember the golden rule, and treat your nausea as a sign of AMS. Trekkers also complain about a loss of appetite during the period and attribute it to dehydration, which you should avoid doing.

During my many expeditions, I’ve often seen trekkers complain about not getting enough sleep, and them tossing and turning in their sleeping bags all night. Now it’s easy for first-timers to blame this sudden outburst of insomnia on a change of surroundings and not being used to tents or sleeping bags. But shivering in your tent and being unable to sleep isn’t normal, especially when your body feels tired and exhausted after having trekked all day. So if you’re unable to sleep, please treat it as a sign of AMS first and foremost. 

 That brings me to my penultimate symptom – Extreme Fatigue. Now I’ve noticed this on many of my treks where a trekker who’s extremely fit and well-paced and ahead of the pack on Day 1 of the trek, feels exhausted and fatigued the next day and is barely able to keep up, and by the end of Day 3, he’s seen struggling for breath and lagging behind while climbing. This isn’t normal, extremely for people who are fit, as they’re expected to maintain a stable pace each day of the trek. If you ever encounter such a situation yourself, please treat the fatigue as AMS first.

The fifth and final sign that goes unrecognized as a symptom of AMS is this inexplicable case of uneasiness or restlessness. I’ve observed quite a few times when a trekker isn’t able to pinpoint exactly what’s going on but they can tell you that something for sure is wrong with their body, and sometimes their mind too. You must be aware of this and treat it as a signal your body is sending you regarding AMS. 

A video that debunks 5 Common Myths About AMS | Altitude Sickness

That brings us to the end. By now I hope you’ve built upon your understanding of AMS and will be better equipped to handle it on your next trek. You must keep in mind that this isn’t an exhaustive list of symptoms and that high altitude affects each person differently. Many people might show a range of symptoms with different intensities. Therefore it becomes critical to stay alert and notify your trek leader or other members in your group and always treat these symptoms as AMS first. Never forget the golden rule. 

If this article got you thinking about AMS, we have a lot of other resources on our platforms. 

To understand how to treat and prevent AMS, you can find the video on our YouTube channel helpful where we talk about AMS in detail, especially its treatment. 

Besides, you can always write to me at trekwithswathi@indiahikes.com  with any queries you might have after reading this piece. Be sure to share this with your trek mates. 

Drop in a comment with your thoughts or questions, if any, and we will get back to you.

5 Signs You May Not Recognise as Acute Mountain Sickness (AMS)

Today’s article is an important one – it’s about how to treat altitude sickness such as AMS, HAPE & HACE.

Before I get into medications and technicalities, I want to share a golden rule with you. And it is not about descending, which most manuals will talk about. It is something you must always remember.

When it comes to altitude sickness, the golden rule is to stop it in its initial stages. The later it gets, the more dangerous it gets, and it could even turn fatal.

To stop it in its initial stages, recognising the symptoms is key.

In another post, I told you how to recognise the symptoms of altitude sickness. If you missed it, read it here.

With that in mind, let’s get on to treating altitude sickness.


You need to carry three absolutely essential Life-Saving Drugs (LSDs) with you on a high-altitude trek. It does not matter if you are trekking alone or with a group.

These are Diamox, Dexamethasone and Nifedipine. In India, you can buy them off the counter in most pharmacies even though these are prescription drugs.

Diamox is a diuretic. To put it simply, it helps speed up acclimatisation.

Dexamethasone (Dex) is a steroid. It prevents your body from releasing substances that cause inflammation. That’s how it helps temporarily treat edema.

Nifedipine is a drug that reduces your blood pressure. You use it only if you have HAPE.

Now let’s see how we can treat altitude sickness i.e. AMS, HAPE and HACE with these LSDs.

How to treat Acute Mountain Sickness (AMS)?

Let’s start with the easier one, Acute Mountain Sickness (AMS)

AMS is the most common form of altitude sickness we see. It starts off with relatively mild symptoms. But if left untreated, it gets severe and could form into either HAPE or HACE. 

You’ve got to absolutely treat it when it’s mild (no rocket science there).

I’ll let you learn about AMS symptoms directly from someone who was hit by AMS. 

It’s the story of my old colleague, Suhas, who was recently on the Devkyara exploration in Uttarakhand.  

He says, “We were at the first campsite, at around 8,500 ft. We had had a long day of trekking, mostly ascending and I was exhausted. Although I didn’t feel like eating much, I took two small rotis (which I couldn’t finish). After eating just one and a half roti and drinking some water, I went to sleep.

In my tent, I kept feeling very queasy and at around 10:30 pm, I finally stepped out of the tent and threw up. The uneasy feeling stayed with me all night and prevented me from sleeping. As I tossed and turned in my sleeping bag, I kept debating whether I should wake someone up, but I didn’t. 

The next morning, after breakfast, I was again not feeling comfortable. I threw up everything I’d eaten. On the trek, when there was an ascent, I started to feel very tired. I was unable to carry my backpack. It was taking me almost double the time that I would normally take to cover the distance. Throughout all this, I never told anyone about my symptoms. Finally, it was Arjun and Sandhya who noticed that all wasn’t well with me.”

What Suhas has said here are classic symptoms of AMS – uneasiness, vomiting, lack of sleep, fatigue, and lack of appetite. Notice how he never told anybody about his symptoms? This is also typical behaviour of someone who has been hit by AMS. Notice, also the rather low altitude.

He didn’t have a headache even for a minute! Most trekkers actually wait for a headache to confirm if it’s AMS. That’s not wise.

So here’s what you need to keep in mind. Drill it in. AMS can climb onto you in different ways. Not all the symptoms may show up (especially headache), but some of them will. Remember, the best way to treat altitude sickness is to recognize it early and take all steps to prevent it from getting worse.

Look out for feeling generally uneasy. Especially a bad feeling in the stomach and a pukey feeling. Look out when your pace reduces (and you’ll know it yourself, but don’t fool yourself into thinking you’ll get over it).

Do also keep an eye out for headaches as they are an indicator of possible AMS.

You need an exceptionally sharp eye to spot these things in others. But if you have AMS yourself, you should be able to identify it. You just need to be aware of the symptoms.

Another way to tell if it’s AMS is if you have a pulse oximeter handy. You’ll find that oxygen levels have dropped. Anything below 85 is usually a low reading. And 83 is not 85. If it is below 85, take steps.

Now, here’s the important thing. Don’t trust the pulse oximeter too much. It is, at the end of the day, just a device. Trust your symptoms more. That’s the only thing we go by in the mountains.

A.) When you have learnt that you have AMS

The first thing you must do if you have AMS is start a curative course of Diamox.  

(I’m using “curative” here as this course is different from a “preventive” Diamox course. I’ll tell you more about that in my next post).

Take 250 mg of Diamox (one tablet). Drink 500 ml of water and rest for an hour. Even if you are mid-trail, try and rest for an hour. Resting is imperative because any kind of exertion depletes your body’s oxygen content.

After this medication, this is what could happen. In an hour’s time, your symptoms may reduce, but may not completely disappear.

So move to your next camp. Take the rest immediately. After 4 hours (of the first tablet) take another dose of Diamox (250 mg). Keep yourself well hydrated. Avoid exerting yourself. Don’t go on sightseeing walks.

In all probability, it is going to be evening by the time you have taken the second dose.

The next few hours are critical. You want to take all the necessary steps before night-fall. If you feel better within two hours of your second Diamox dose, then your body has started to acclimatise. But continue to be on a course of Diamox (250 mg), every 12 hours for the rest of your trek, starting that night. If you are not feeling better, do not panic. We go to the next level of medication. 

At around 9.00 pm take another dose of Diamox (again, 250 mg). Also, take 1 mg of Dexamethasone (we’ll call it Dex from now on). Dex is going to help reduce inflammation in your body that causes these altitude sicknesses. The Diamox and Dex combination will help you sleep better.

The next morning, you have to make a decision.

If you have slept well and feel better with none of the uneasiness, your body has acclimatised.

Continue your trek but be on a course of Diamox (250 mg) every 12 hours starting that morning. End the course only after you complete the trek.

Remember, it is important to be honest with yourself at this stage. Continuing on the trek while feeling uneasy can lead to further complications. Additionally, don’t worry about your money, given the circumstances you will be allowed to come back for the same trek for free. (Refer to our trekking policy).  

If you still have a lingering sense of uneasiness, then it is time to accept that your body is not acclimatising despite medication.

Start your descent. Continue to descend until you have got yourself to an altitude of around 8,000 feet. This may take time. But the good thing is that with every 1000 feet that you descend, you’ll feel better.

A word of caution. Just because you start feeling better, do not stop your descent. An abrupt stop can make your AMS come back.  

Now, that’s how you treat altitude sickness such as AMS. It really isn’t difficult. Monitoring symptoms is everything!

How to treat High Altitude Pulmonary Edema (HAPE)?

2. How to treat High Altitude Pulmonary Edema (HAPE)?

The symptoms of HAPE are very distinct, but you could miss them if you’re not paying attention.

There are two things you should be able to catch – cough and breathlessness.

If you have HAPE, you’ll cough a very dry cough every now and then.

Next, notice how you walk around the campsite. If your movements are laborious or your breathing is heavy, it is a big warning shoutout. You may even notice yourself breathing heavily while sitting. Anything will tire you. There is always a feeling of fatigue.   

These are the initial stages of HAPE. It is during these stages that you must recognise HAPE and start treatment immediately.

I hate to say it but if there is any symptom beyond this – like the rattling sound from the chest, or blue-ing nails and lips, then HAPE has advanced. And HAPE escalates very quickly.

To treat altitude sickness such as HAPE, you need Diamox and Nifedipine. (I’m writing this assuming that you may not have canned oxygen with you as our Trek Leaders do. Supplementary oxygen can also work wonders while evacuating a HAPE patient.)

When you have identified HAPE, take 500 mg of Diamox immediately (even if you have taken Diamox a few hours earlier). We are talking about two tablets.  

Follow it up with 20 mg of Nifedipine. In India, we mostly get 10 mg tablets of Nifedipine. So take your first 10 mg, wait for 20 minutes and then take the next 10 mg.

This will let the tablet settle in slowly. Within 30 minutes of the second 10 mg, you should be able to breathe easier.

Nifedipine reduces the pressure in your heart and blood vessels. If you remember, I told you that HAPE occurs because of high pressure around the lungs, when the air sacs start accumulating fluid from your blood.

Nifedipine eases out the pressure around your lungs, giving it some space to breathe.

With these two tablets in your system, start descending. You should try to lose as much altitude as possible over the next three hours.

If you cannot reach around 8,000 ft even after six hours, repeat the dose of 500 mg Diamox and 20 mg Nifedipine and continue descending.

You’ll be tired, but it’s a matter of life and death. You need to be at a lower altitude.

Most trekkers recover upon reaching lower altitudes. You’ll recover too.

Again, it’s very important to remember that the best way to treat altitude sickness is by keeping an eye out for your symptoms and taking the necessary steps such as descending to a lower altitude. You do not want HAPE to escalate.

How to treat High Altitude Cerebral Edema (HACE)?

3. How to treat High Altitude Cerebral Edema (HACE)?

The key to the treatment of any altitude sickness is early detection. The earlier you catch the symptoms the faster you can take steps to ensure the altitude sickness is controlled.

It isn’t hard to detect HACE. With HACE, almost always, you’ll have a bad headache (because HACE is a swelling of the brain). You’ll find it hard to do daily activities such as just zipping up your tent, or putting on a jacket. In addition, you may appear dazed and confused to others, saying irrational things. You might keep forgetting things too.

You may also continue to feel pukish with a general uneasiness.

All these are symptoms of HACE. It means your brain is swelling with an accumulation of fluid.

Like HAPE, there’s no treatment to cure HACE. What you can do is prevent its acceleration and keep it from turning fatal. The only way out of HACE is to descend and lose as much altitude as soon as possible.

To help you do that, start with a 500 mg dose of Diamox and around 4mg of Dex. This combination will stop your brain from swelling, giving you a window of a few hours to get yourself out of that altitude.

Start your descent immediately. Try to get to an altitude of around 8,000 feet as soon as you can.  

If you still cannot reach lower altitudes after six hours, repeat the same dose and continue your descent.

Don’t stop until you have reached around 8,000 ft. Once you have reached a lower altitude, lower your dosage of Dex to 2 mg, followed by 1 mg every 6 hours. Dex needs to be weaned away and cannot be stopped immediately.

What you should know about altitude sickness

Altitude sickness is not something that is too difficult to understand or treat. The main problem that plagues the trekking community is the lack of knowledge about it.

Through this post, I hope you have learnt what to watch out for and how to tackle any symptoms.

Of course, it’s not easy to figure things out overnight. It requires years of experience to actually put a finger on the issue and treat it. But with a basic understanding of the science behind it, there’s a lot you can do to make someone with AMS feel better and save him.

Also, know that communication is the key to treating AMS!

If you’re trekking with Indiahikes, always keep your Trek Leader informed of your symptoms. You’ll, of course, have your own Health Card to keep track of your vitals and your symptoms.

The most important thing when it comes to treating altitude sickness is the need, to be honest, and vocal about your symptoms. Failing to mention your concerns or potential symptoms to trek leaders is a massive disservice to yourself. Our trek leaders are well-equipped to treat altitude sickness and the earlier they know the faster they can act.

If you’re trekking solo or with a group of friends, then it’s imperative that all of you have this knowledge of treating altitude sickness. Share this article with them. 

After reading this, head over to the most helpful post of them all, on how to prevent Acute Mountain Sickness altogether!

How to recognise symptoms and treat altitude sickness, Acute Mountain Sickness, High Altitude Pulmonary Edema & High Altitude Cerebral Edema

How To Treat Acute Mountain Sickness (AMS), High Altitude Pulmonary Edema (HAPE), High Altitude Cerebral Edema (HACE)

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Today I’m talking about a term we’re all familiar with — altitude sickness.

Before you read this, I hope you’ve read my previous article about how altitude affects your body. If you haven’t, then read it now. It is important that you know some background first. You’ll find it here if you missed it.

What is altitude sickness?

Interestingly “altitude sickness” itself doesn’t mean much.

It is a blanket term for different kinds of illnesses — it could be something as simple as a slight swelling in your fingers to something as severe as fluid accumulation in your brain.

For the most rudimentary understanding of the term, “altitude sickness” means that your body is not adjusting well to altitude.

With that in mind, today, I’ll talk about the most common forms of altitude sickness we see on our treks — AMS, HAPE and HACE.

Let’s start with the mildest form and progress to the more nasty forms.

What is Acute Mountain Sickness (AMS)?

1. What is Acute Mountain Sickness (AMS)?

AMS is very common when you’re trekking in the Himalayas.

Well, in a team of 20, we see at least 3-4 people showing symptoms of AMS. Most of them recover within a few hours.

We’ve also noticed that all of them don’t show symptoms at the same time. Some of them might show symptoms at a lower camp, some at a middle camp and some at a higher one.

Some show symptoms even while descending!

But it’s something you should keep in mind. AMS doesn’t always affect you while ascending. It might have hit you at your previous campsite or at the highest point on your trek, and the symptoms might show up the next day when you’re descending.

So you have to be vigilant at all times. There’s no way out of it.

Getting to the symptoms, I’ll tell you what we see most often.

Most trekkers affected by AMS display gastrointestinal symptoms. They either go to the loo very often, or they feel nauseous. They sometimes vomit. Especially late in the evening or after bedtime.

In our experience, GI symptoms (gastrointestinal) are a lot more frequent than the notorious headache that all manuals will tell you about.

Having said that, we have seen trekkers suffering from persistent headaches too. It builds up while trekking. It persists through the afternoon and evening. Most confuse it with dehydration. Or they assume it’s the heat. Most often they are right, but they could be very wrong too.

You’ll often hear them saying “I’m feeling uneasy.” They won’t be able to explain that uneasiness.

There are more symptoms — fatigue, loss of appetite, dizziness.

Of the three, look out for trekkers who are supercharged on day one and suddenly lagging behind on day two. (They’ll most likely tell you that they’re slow because they are taking in the scenery. Most of them don’t like to admit to any symptoms.)

Watch, especially, for not wanting to eat.


What I’ve learnt is that when you’re at high altitude, any symptom you have must first be attributed to AMS and then to anything else.

If these symptoms are treated immediately, AMS can be cured and the trekker can proceed further. Most of our trekkers who have mild AMS go on to complete the trek after medication.

A video debunking 5 Common Myths About AMS | Altitude Sickness

If left untreated and ignored, mild AMS could transform into its more sinister cousins – HAPE or HACE.

What is High Altitude Pulmonary Edema (HAPE)?

2. What is High Altitude Pulmonary Edema (HAPE)?

Edema --> An abnormal accumulation of fluid in parts of the body

HAPE is an advanced form of AMS. And a more dangerous form.

I really would not want to see you or anyone getting HAPE. This is when things have started to turn nasty. It requires a very experienced hand to get you out of this mess.

I’m saying this because HAPE can and does turn fatal very quickly. I am not trying to scare you. These are things that happen at high altitudes.

When a trekker has HAPE, fluid from his blood leaks into air sacs in his lungs (because of high pressure in the arteries of his lungs).

To put it simply, HAPE is like death by drowning. The trekker’s lungs are drowning in his own body fluids.

And when his lungs are incapacitated, you can imagine what could happen. The rest of his body will soon stop functioning.

The symptoms of HAPE start off much like AMS symptoms, with fatigue, loss of appetite and difficulty in breathing.

But HAPE could appear suddenly without AMS preceding it too. It’s very normal for HAPE to climb onto a trekker within hours — we notice that it worsens at night when the trekker sleeps and his breathing becomes shallow. So sleeping at high altitudes with mild HAPE is a big NO.

For this, identifying the symptoms is very important. And the symptoms of HAPE are pretty evident.

The HAPE-affected trekker is absolutely exhausted. He/she finds it difficult even to go up to the toilet tent. His breathing is heavy, even during mild walks. An experienced trekker will hear him breathing hard even while sitting.

He coughs quite a bit. A dry kind of cough. Not often, but obvious enough.

And here’s the final, sure-shot evidence: When you put your head to his chest, you’ll hear a rattling, gurgling noise. You don’t need a stethoscope. You just need to keep your head near his chest.

Scary as it might sound, there’s light at the end of the tunnel — HAPE does not occur too regularly. And it can be treated. At Indiahikes, in the last two years, we have seen just 15 cases of HAPE on our treks. All of them were evacuated to safety.

The key lies in identifying symptoms as early as possible and acting quickly.

It’s a similar case with HACE. Let’s talk about that next.

What is High Altitude Cerebral Edema (HACE)?

3. What is High Altitude Cerebral Edema (HACE)?

HACE is as serious as HAPE because the altitude is now playing with your nerve centre.

When a trekker is affected by HACE, his brain starts to swell. This happens because blood vessels in the brain dilate, filling the brain with fluids.

Since HACE affects the brain, the symptoms are clearly identifiable.

A headache is almost universal amongst trekkers who have HACE — a headache that won’t go with any medication.

You’ll find affected trekkers acting a little strange — they generally talk excitedly or show irritation. Their behaviour is sometimes quite irrational. One trekker we know asked for a helicopter to evacuate her. This sounds rational, but when you know the trekker’s normal behaviour, she would never say something like that.

They sometimes walk woozy, as if sloshed after a night of drinking.

This is medically termed ataxia, where the brain tells the body something, but the body does something else. It’s a basic loss of muscular coordination.

You may also see them struggling to talk, hallucinating, unable to see clearly.

Don’t ask a trekker affected by HACE to do simple maths, like 5+3. They have been affected by HACE, but they are not idiots. They will get it right but may still be affected by HACE.

A trekker who’s been hit by HACE deteriorates within hours and could go into a coma.

So it’s important to act before it gets severe.

Thankfully, HACE is very very rare. From January 2017 until September 2024, we have seen just two cases of HACE. 

What do you need to know about altitude sickness?

What you need to know about altitude sickness?

Well, altitude sickness depends a lot on how fast you gain altitude, your physiology and your body’s capability at the time of your trek

Altitude sickness does NOT depend on your prior high altitude experience, your fitness preparation or the food you eat.

Having said that, we have noticed that those who are better prepared for the trek get affected less. Their lungs are prepared to work harder despite having less oxygen.

When Sandhya UC suffered from altitude sickness

Our co-founder, Sandhya — a fit, experienced and healthy eater, suffered from a bad case of altitude sickness in the form of AMS at a relatively low altitude on the Buran Ghati trek. Thankfully, she knew of the symptoms and medications and could rescue herself from the clutches of AMS. Read about her AMS experience here. There is a lot to learn from her.

What I’m trying to say is that anyone can be affected. And anyone can save themselves or others. All it requires is knowledge.


What is altitude sickness - Detailed symptoms of Acute Mountain Sickness, High Altitude Pulmonary Edema and High Altitude Cerebral Edema.

Acute Mountain Sickness

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