You should limit the speed at which you ascend by taking as much time as possible for acclimatisation. From experience we know that between 2500 and about 4000 metres is a safe climbing speed for almost everyone. 300 metres per day is. The speed of ascent means the difference in sleeping height between two day's stages. As it takes an average of 4-12 hours for altitude sickness to develop after an ascent, when passing a high pass in between, there is no additional risk of altitude sickness. Many people can climb up to 500 m sleep height difference per day without any problems. However, an average of 65% of climbers to 4000 m in altitude experience brief symptoms that fit with altitude sickness. It is therefore even better, if you come from sea level, to build in an extra day of rest somewhere between 2500 and 4000 metres, or to walk or sleep a day at the same altitude. Keep in mind that in spite of these precautions, very sensitive people can become altitude sick. During the day you can climb 1000 m, as long as you return to a lower level in the evening. Experienced climbers do this in order to adapt better to the altitude. Hence the saying 'Climb high, sleep low'. Above 4000 metres, some experts recommend an even calmer ascent rate of 150 metres per day, but others say that most climbers can cope with 300 metres, especially if rest days or days at the same level are included in the itinerary. Research and experience have clearly shown that above 4000 metres your body often does not allow a higher climbing speed than 300 metres per day with impunity, precisely because of the shortage of oxygen.
Pre-acclimatisation in a high altitude tent
If you are going to climb more than 300m per day during your expedition, there is an effective way to acclimatise your body to the altitude beforehand, namely by sleeping in an altitude tent. You can significantly reduce the risk of acute altitude sickness by acclimatising your body to the altitude in the weeks before your expedition.
Medication
There are a number of indications where medication can be used to avoid altitude sickness:
- When the acclimatisation rules cannot be followed and acclimatisation at home in a high altitude tent is not possible.
- With increased susceptibility to altitude sickness (known from previous experience)
Medication could then be an alternative for correct acclimatisation. However, it remains medication, and it must therefore be taken according to the instructions: side effects/allergic reactions may occur, and one cannot suddenly start climbing Mount Everest with it: medicines are no panaceas.
With this in mind, the following medicines in the following doses work to prevent altitude sickness or its symptoms:
1. Acetazolamide/Diamox
- 125 mg oral administration / 12 hours [Adults]. 2.5 mg per kg / 12 hours [Children] Maximum dose: 125 mg per administration.
- Start the dosage 24 hours before going to altitude. Continue taking the medication during ascents until acclimatisation (± 48 hours) has taken place to 3000 m, and continue until 2 days after reaching the maximum altitude (25).
2. Dexamethasone
- 4 mg oral administration / 12 hours. Maximum use: 10 days.
- Dexamethasone is mainly used when acetazolamide is not advised or when rapid increase is unavoidable.
- If stopped too soon, the symptoms may return (rebound effect).
3. Ibuprofen
- Dosage up to 600 mg / 8 hours. For prevention of AMS (headache).
- Should be used for up to 48 hours after reaching the highest altitude.
4. Paracetamol
- Dosage of 650 - 1000 mg / maximum 4 times a day. To combat AMS headaches.
5. Ondansetron
- Dosage: 4 mg /4-6 hours. For prevention of nausea and vomiting.
