Altitude

As we ascend to higher altitudes the pressure of oxygen in the air decreases. Although the body can adapt to this change (or acclimatise) it can take time. Symptoms of altitude sickness can occur as a result of the decreased availability of oxygen. The number of people travelling to high altitude regions is increasing and many of these places are being easily reached by air, not giving the body sufficient time to acclimatise. Travellers to high altitudes should be aware of altitude sickness and take appropriate precautions. Every year unnecessary deaths occur from altitude sickness.

Altitude Sickness

Altitude sickness or Acute Mountain Sickness (AMS) describes a number of symptoms that can occur if you ascend to altitude too quickly. AMS is infrequent at altitudes below 2500 m above sea level. At 3500m 50% of travellers will feel unwell and at 4300m nearly all travellers will feel unwell. Symptoms usually develop within a few hours, reach a maximum at 12-48 hours and settle in 3-4 days at static altitude. The key to prevention is to recognise the symptoms early.

Symptoms

• headache dizziness loss of appetite
• generally feeling unwell nausea palpitations
• shortness of breath drowsiness loss of balance
• A safe general approach is that if you are not feeling well at high altitude, it is altitude sickness until proven otherwise.

Prevention

It is the rate of ascent that is critical in preventing AMS - you must ascend GRADUALLY.

The general rules are: -

• above 10,000 feet (3200m) ascend 1000 feet or 300m maximum per day.
• after every gain of 3000 feet (1000m) have one rest day.
• these are minimums - listen to your body and go more slowly if necessary.

Other helpful hints:

• drink lots of fluids
• eat a high carbohydrate diet
• sleep lower than the maximum altitude reached during the day
• avoid alcohol as it causes dehydration and reduces your ability to breathe
• avoid smoking
• avoid sedatives at night

Unfortunately, there is no way of predicting whether you will be initially prone to altitude sickness, and your susceptibility is not related to your age, fitness or general health. Children are 6-10 times more likely to get AMS and people who have had AMS before have an increased risk of redeveloping AMS on subsequent ascents.

Management Of Altitude Sickness

If you have severe symptoms of altitude sickness, the best treatment is to DESCEND. If you only have mild symptoms, there are a few things that may help you feel better - rest, drink plenty of fluids, take paracetamol for your headaches, avoid strenuous exertion, and avoid alcohol. After 1 to 2 days at the same altitude, you will probably acclimatise and start to feel better. When symptoms have settled you may ascend slowly. If your symptoms don't settle or if you feel worse, you should descend.

Never ascend if you have severe symptoms of Altitude Sickness

Diamox (Acetazolamide)

This medication is commonly used by travellers to high altitude, and is safe if used with caution. There are two ways in which you can use Diamox:

1. Prevention: If you have travelled to high altitude areas before and know that you will experience symptoms at a certain altitude, you can start taking Diamox,half a tablet morning and night, a day before you reach that altitude. This will reduce the severity of your altitude sickness symptoms. It is also often used if people are gaining altitude very quickly, and are therefore at higher risk of developing problems, e.g. flying from sea level to La Paz which is at 3200m. Prevention can be taken for 3-4 days at which time many people have acclimatized or until maximum altitude has been reached.
2. Treatment : Some people prefer not to take Diamox preventatively, and want to see how their bodies cope at high altitude. Many people will not require any medications. However, if you start to feel unwell at high altitude, it is still possible to start taking the medication then. It can work quite quickly, and you may start to feel better within a couple of hours. It is useful to carry this medication with you if you are travelling to remote areas, because it may not be easily available if and when you need it.The treatment dose is one tablet twice/day
3. Duration: The Diamox can be continued until you commence your descent,and so duration will vary according to climbing profile.Most people will have acclimatized within one week of stay at their highest point.

Side-effects of Diamox:

Most side-effects are mild, if you experience them at all. The most common ones are frequent urination, and tingling around your lips and on your hands and feet. It is a sulpha based drug, and should not be used if you are allergic to sulphas. If you are on medications, please check with your doctor to make sure that it is safe for you to take Diamox.

Other Problems At Altitude

Altitudes Of Some Cities And Mountains

Updated August 2021.