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 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.
Immediate descent is essential (even in the middle of the night).
A descent of as little as 300 metres can mean a matter of life or death.
After descent, specialised treatment with oxygen chambers and medications can be given by experienced medical personnel.
It is the rate of ascent that is critical in preventing AMS - you must ascend GRADUALLY.
The general rules are: -
Other helpful hints:
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.
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
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:
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.
|Dehydration||You lose far more fluid at altitude than you realise. It can make you feel dizzy, tired and give you a headache. Drink at least 2 litres of fluid per day, avoid alcohol and make sure your urine output is clear and copious.|
|Skin problems||Sunburn can be severe. Due to the thinner air, the sun's rays are much more intense. Use a 15 SPF+ sunscreen regularly. Certain drugs eg Doxycycline may cause photosensitivity (increased sunburn risk). Dryness - use a good quality moisturiser.|
|Snow blindness||Using good quality sunglasses or goggles can prevent this.|
|Swelling||Puffiness of eyes, hands and feet is common at altitude. If you are otherwise feeling well this is not serious and will go away on descent.|
|Heart and Lung problems||These may be worse at altitude. Check with your doctor.|
|Thrombosis/ Blood clots||Blood thickens at higher altitudes and there is a higher risk of clots forming, particularly in your leg veins or lungs. Other risks include smoking, the contraceptive pill and previous clots. Discuss your risks with your doctor.|
|Muscle and joint pain||Trekking and skiing often involve being at altitude. Old injuries may cause problems. Speak to your doctor before leaving if you are concerned.|
|Cities / Mountains||Metres||Feet|
|Mt Kosciuszko, Australia||2228||7310|
|Mt Cook, New Zealand||3754||12316|
|Mont Blanc, France||4807||15771|
|Mexico City, Mexico||2308||7572|
|Lhasa, Tibet 3685 12090|
Updated August 2021.