How to prevent altitude sickness

Altitude sickness (also known as high-altitude sickness or Acute Mountain Sickness, AMS) is a valid concern for any trekker venturing to a high altitude.

Altitude sickness is caused by the low oxygen levels present at higher altitudes, usually those above 2,500 metres. It occurs when your body has not had enough time to adjust to the lower amount of oxygen, which can lead to symptoms including headaches, nausea, and dizziness.

Read on to learn what you can do to reduce your risk of altitude sickness, support acclimatisation, and manage symptoms safely while trekking, and don’t forget to check out our FAQs at the bottom of the page for more information.

While this guide focuses on how to prevent altitude sickness, it’s important to be clear: altitude sickness can never be completely ruled out. Even fit, experienced trekkers can still experience symptoms at high altitude.

Experiencing mild symptoms doesn’t automatically mean your trek is over. Headaches, tiredness, loss of appetite or poor sleep can happen at altitude and may improve with rest, hydration and time to acclimatise. However, symptoms should never be ignored or pushed through in silence.

If you feel unwell at altitude, tell your guide as early as possible and follow their advice. In some cases, the safest option may be to rest at the same altitude, take treatment, slow the pace, or descend if symptoms worsen or don’t improve.

On EverTrek trips, acclimatisation days are built into the itinerary, and your guides are experienced in spotting the signs of altitude sickness and knowing when extra rest, treatment or descent may be needed.

1. Watch your pace

When you're trekking at high altitudes, it's essential to manage your body in a way that enables it to safely adjust to the increasing altitude and lower oxygen levels. One of the best ways to do this is to pace yourself.

The slower you go, the easier it will be to breathe. It can be psychologically tough to consciously go slower, especially if you're used to trekking at a faster pace, but it's crucial to slow down to allow your body to acclimatise to the high altitude.

You should aim for a pace where you can hold a conversation without being out of breath. Your guides will also keep a watchful eye on your pace and offer advice if they feel that you're going too quickly.

2. Don't skimp on hydration

Staying hydrated is crucial when trekking at high altitudes. If you're struggling with the high altitude, it's likely that you haven't drunk enough water.

You should aim to drink at least four to five litres of water per day. While this may seem like a lot, it can be the difference between making it to your chosen summit/destination or not.

The more hydrated you are, the better your body will adjust to the high altitude. A great tip to make drinking water more palatable is to bring small squeezy bottles of squash with you for the trek. These add flavour and make staying hydrated that much easier!

3. Avoid alcohol on the way up

If you're in Nepal trekking to Everest Base Camp, you could have a celebratory drink in the world's highest Irish pub in Namche Bazaar to toast to your success. Or, in Tanzania, you could share some bubbly and beers with your guides following your successful summit of Kilimanjaro.

Check out the video below and transport yourself straight to the post Kili summit celebrations - Tanzania style!

4. Remember to eat

Eating well is also key for preventing altitude sickness, and you should aim for five portions of fruits and vegetables a day.

When trekking in Nepal, it's also best to stay away from meat, as the refrigeration is not quite up to Western standards, making it easy to get sick while trekking.

Taking multi-vitamin tablets to help your immune system can also be helpful, with a particular focus on iron, vitamin B6, vitamin C, and vitamin E for preventing altitude sickness.

5. Consider taking altitude sickness medication such as Diamox or aspirin

Diamox is an altitude sickness medication that can reduce the negative effects of altitude sickness. It's a bit of a contentious subject in the trekking and climbing industry, but it has been proven to work wonders at high altitudes.

It can help trekkers who are struggling to adjust to high altitude; however, it's important to consult with your GP or a local travel clinic before taking Diamox.

Taking aspirin can also treat and prevent high-altitude headaches, one of the most common symptoms of altitude sickness. It does this by reducing prostaglandins (elevated during scenarios of acute hypoxia), which can ease headache symptoms and encourage the body to adapt and adjust to higher altitudes.

6. Have a positive mindset

It’s completely natural to feel anxious about altitude sickness. However, if you come onto the trek constantly worrying about altitude sickness, it will likely have a negative effect on your stamina and mindset.

You've really got to try and stay in a positive mindset. Prepare using the above tips and try to focus on enjoying where you are. You'll soon forget the odd headache, and you will have a much better time.

That being said, if things do become serious or you have any concerns about your altitude sickness symptoms, our guides will always look after you and be on hand to give you the best advice. They are hugely experienced at high altitude and are well trained to notice the signs and symptoms of altitude sickness.

We also factor in acclimatisation days into all of our high altitude treks, giving the body the time it needs to safely adjust while reducing the risks of altitude sickness.