The most important precondition and the best way of avoiding altitude sickness whilst trekking in Nepal is to increase altitude gradually and systematically. In Nepal, a safe altitude to which you can climb rapidly and straight away is: 2,700 – 3000 metres. The most popular mountain airports in Nepal are located in this altitude range: Lukla and Jomsom. On the day of your arrival, you must definitely spend the night at the same altitude.
Thereafter you must stick to a set climbing regime: 300 – 400 altitude meters a day. Accordingly, every overnight stay must be at an altitude of 300 – 400 metres higher than your previous overnight accommodation. Having climbed a total of 1,000 altitude metres, you must devote one whole day to altitude acclimatization and stay overnight at the same altitude. It is advisable to spend the day of altitude acclimatization doing a little trekking leading up to a short stay at a greater altitude (300 – 400 m) before returning and staying overnight at the previous altitude. In Nepal, you will not find it possible to stick to exactly this climbing regime on all trekking routes in the Himalayas, therefore altitude acclimatization days are individually planned for each trekking route.
2nd altitude acclimatization rule: consume lots of liquids while trekking
In the mountains, atmospheric pressure falls as the altitude above sea level increases and this affects your body. Therefore, when trekking in the mountains it’s very important to consume a lot of liquids by drinking lots of tea, juice, soup, and clean water. You should drink at least 3 -4 liters of liquid a day. You can buy a liter of bottled water in teahouses along all the most popular trekking routes in Nepal. You should avoid drinking too much black tea while trekking, as well as giving the coffee a miss on tough days because these drinks can induce heart palpitations and create additional pressure on your heart.
3rd altitude acclimatization rule: avoid alcohol, smoking and using sleeping tablets
When trekking in the mountains, particularly during your ascent you must categorically avoid the use of alcoholic drinks and sedatives or sleeping pills. Like smoking, sedatives artificially reduce the flow of oxygen to the brain, particularly in mountain conditions in which the concentration of oxygen is already reduced. In turn, alcohol has the heightened effect of depriving the body of water or dehydrating it which is a similarly undesirable process when trekking in the Himalayas in Nepal.
4th altitude acclimatization rule: use preventive medicines whilst trekking
Mountain medicine has discovered a range of medicinal products that improve the altitude acclimatization process and reduce the side effects of altitude acclimatization in the mountains such as sleepless nights. These products are widely used by trekkers on popular trekking routes in Nepal like the Everest Base Camp trek, Gokyo trek, Annapurna Circuit trek, etc.
Acetazolamide or Diamox®
Of all the medicinal products use to aid altitude acclimatization and treat altitude sickness the most popular is Diamox, whose active substance is Acetazolamide. On the Everest Base Camp trek, Diamox is widely on sale without a prescription in Kathmandu, Lukla, and Namche Bazaar. One strip of Diamox contains 10 x 250 mg tablets and in Nepal, you can buy it for 150 – 200 rupees.
Possible alternative names (trademarks) for Acetazolamide include: Acetamox, Acetazolam, Ak-Zol, Apo-Acetazolamide, Atenezol, Cidamex, Dazamide, Defiltran, Dehydratin, Diacarb, Diakarb, Diamox, Didoc, Diluran, Diuramid, Diureticum-Holzinger, Diuriwas, Diutazol, Donmox, Duiramid, Edemox, Eumicton, Fonurit, Glaupax, Glupax, Natrionex, Nephramid, Nephramide, Phonurit, Storzolamide, and Vetamox.
Before trekking it is advisable to start using Diamox 24 hours before your ascent and once you’ve started trekking you should use Diamox twice a day in doses of 125 – 250 mg depending on your body weight in the late morning and in the evening. Kids should be administered a Diamox dose of 2.5 mg per kg of body weight twice a day. It’s important to take Diamox before going to bed, because it deepens the depth of inhalation during sleep, thus improving the body’s supply of oxygen. Diamox is an effective means of preventing pulmonary oedema.
It’s true that Diamox can cause some side effects of which the most common are light tingling of the hands and finger tips, blurred vision, etc. Diamox can also induce allergic reactions; therefore it is recommended that you consult your doctor before use. According to some sources, you should stop taking Diamox on the second or third day after reaching the maximum height on your trekking route, while others say that it is not recommended to use Diamox for longer than 3 -5 days in a row. Based on my own experience during the Everest Base Camp trek, I would recommend starting to think about using Diamox upon reaching Namche Bazaar (3,440 m).
In traditional medicine, Acetazolamide is also used to treat epilepsy and glaucoma.
Ginkgo biloba extract
Studies of the effectiveness of Ginkgo biloba extract during the altitude acclimatization process and of its impact in mountain conditions are still continuing, but experiments have shown that it is effective in helping to reduce symptoms of altitude sickness during trekking. Ginkgo biloba functions as an antioxidant, reducing stress and the supply of oxygen to the brain.
It is recommended that you start using Ginkgo biloba extract at least five days before climbing in doses of 80 – 120 mg twice a day and that you continue using it in the mountains.
Ginkgo biloba extract is a natural product made from ginseng and may be used for prophylactic purposes to improve the functioning of the brain and not just in mountain conditions. It can be bought in pharmacies as a nutritional supplement without prescription.
One of the best natural recipes for aiding altitude acclimatization that is often recommended by trekking guides in Nepal is garlic and the popular garlic soup served in Nepal’s trekking lodges and teahouses. At first it is likely to taste quite strange, but as you get used to it – you’ll begin to get a taste for it. Garlic soup is also widely available along the Everest Base Camp trek route.
5th altitude acclimatization rule: avoid overexertion from carrying overly heavy rucksacks whilst trekking
Bearing in mind the physical strain and changes in mountain conditions, whilst trekking you would be well advised to avoid overexertion and leave the carrying of your heavy bags to bearers. This doesn’t cost much and you can hire a Sherpa to carry your bags on almost any stage of the Everest Base Camp trek starting from Lukla right through to Pheriche or Dingboche. If you still plan to carry your own rucksack; optimally its weight should not exceed 10 -12 kg.
6th altitude acclimatization rule: don’t go trekking alone
You should always take a guide with you when trekking in the mountains. Altitude sickness symptoms can induce panic or wild behavior so you must have somebody alongside you who can help you at any time you find yourself in trouble. Typically, altitude sickness symptoms get worse at night due to problems acclimatizing to the new altitude reached during the day. If symptoms of altitude sickness force you to depart and descend at night, you simply must have your guide with you at all times!
7th altitude acclimatization rule: don’t climb higher even if you are only suffering from mild symptoms of altitude sickness
If, after reaching a new altitude on your trekking route, you begin to experience mild symptoms of altitude sickness, you must not climb higher under any circumstances! You must remain at your current altitude and monitor your symptoms. Usually, altitude sickness symptoms begin to appear 6 -12 hours after reaching a new altitude. Symptoms start appearing in the form of a mild headache which may disappear in a few hours, or, on the contrary, get worse, accompanied by panic, loss of appetite and nausea. Trying to fall asleep you experience wild dreams and mild hallucinations.
During this period, even though you’ve lost your appetite, it’s very important to drink a lot of fluids and to eat, if you haven’t already done so. Garlic soup is recommended as well as Diamox or some headache tablets which liquefy blood and improve blood flow: Paracetamol, Aspirin, Tylenol or Ibumetin.
A real example of inadequate altitude acclimatization was that which I personally experienced during my Everest Base Camp trek. The first altitude acclimatization day (a rest day usually occurs at Namche Bazaar, but we skipped it and next day continued climbing to stay overnight at Khumjung (3870 m) which is 400 m higher than Namche Bazaar. We completed that day’s trekking at about 16:00 and stopped at a Khumjung teahouse. Gradually I began to feel a light all-encompassing pressure at the top of my head which left me feeling as if I was wearing a swimming cap.
Gradually the pain grew stronger in my forehead, but at about 22:00 when I was getting ready to fall asleep, I was overcome by a feeling of alarm that I’d never felt before and a slight case of nausea. It was as if I was short of air. I took some Diamox, drank a lot of fluids and headed to the teahouse’s big bedroom to sleep because it was cooler there. I struggled with sleeplessness and nightmares for another few hours and only fell asleep towards morning. The next day I ate breakfast and felt a lot better again. We continued trekking because the planned altitude regime along the route favored the continued altitude acclimatization process.
It was a mistake to climb higher without a full day’s altitude acclimatization at Namche Bazaar.
8th altitude acclimatization rule: descend immediately if your altitude sickness symptoms get worse
If the usual painkillers used to treat headaches (Aspirin, Tylenol, Ibumetin, etc.) don’t help and your headache doesn’t pass, this indicates that the altitude sickness is getting worse. In the event that upon reaching a new altitude along the trekking route the symptoms of altitude sickness don’t pass and get worse; the most effective treatment is to descend without delay to a lower altitude. You must descend without delay even at night. You must be accompanied by your guide and take everything with you that you need for the journey. Under no circumstances should you descend alone. At the Himalayas Khumbu region Machermo HRA Medical Point, I heard a story about a trekker who died at night after falling into a gulley from a narrow or icy hill path whilst suffering from altitude sickness resulting in a loss of balance and sense of disorientation.
In such circumstances you should reduce your altitude to at least the altitude at which you made your previous overnight stay where you didn’t notice any signs of altitude sickness and, if possible; descend even lower. You will feel the benefits after reducing your altitude by 500 – 1,000 altitude metres. You should use medicines, additional oxygen, and your compression bag or Gamow Bag if you have them available.
9th rule: never leave anybody alone with signs of altitude sickness
Never leave a person showing signs of altitude sickness alone. He could begin to experience rapidly deteriorating altitude sickness symptoms and it may be necessary to urgently evacuate him to a lower place.
10th acclimatization rule: dress warmly when trekking and don’t overexert yourself
You should keep warm at all times when trekking and prevent your body from cooling, particularly during the first stage of altitude acclimatization. Check to make sure that your clothing is always dry. In the mountains the air is dry and it’s usually windy.
As sweat evaporates, it increasingly cools the body, narrowing arteries and reducing the supply of blood and oxygen reaching your organs, thus creating conducive conditions for altitude sickness to get worse. Special technical clothing has been invented for trekking in the mountains, which ensures that the body breathes and gets rid of sweat as effectively as possible.
By observing all of these rules, trekking in Nepal, especially the Everest Base Camp trek will be a fun experience and you’ll arrive home with fantastic memories and impressions of your time in Nepal and the Himalayas.
If you have any specific questions about altitude acclimatization along Nepal’s trekking routes, please feel free to write to me and I’ll get back to you as soon as I can.