Altitude sickness, also called Acute Mountain Sickness (AMS), is an illness caused by exposure to the low air pressure; especially low partial pressure of oxygen, which many climbers experience at high altitudes.
There are a number of practical steps that you can take to minimize the chances of having to abandon your climb of Kilimanjaro due to the effects of altitude sickness:
Acclimatize prior to the climb.
Easier said than done if you live at sea level but if you are able to spend time at high altitude prior to the actual Kilimanjaro climb then this is the very best way to avoid altitude sickness. Climbing Mount Meru prior to Kilimanjaro is also an excellent option.
Start the climb in the best possible health and with an excellent level of physical fitness. If you are fatigued, unwell or stressed you are more likely to suffer from altitude sickness.
Slow and steady.
You need to keep your respiration rate low enough to maintain a normal conversation. If you are panting or breathing hard, you must slow down. Overworking your heart and lungs substantially increases your chance of becoming ill.
Drink much water as you can.
Getting up in the middle of the cold night may be an unpleasant thought but altitude dehydrates you and the better you hydrate the quicker your body is able to acclimatize.
Even though you may not feel like it you should eat as much as you possibly can at every meal. This will give you plenty of energy and help you to feel great. I find it also helps me to keep warm and sleep well at night.
Sleeping well in a tent is a acquired skill. Spend a few nights out in your tent and sleeping bag prior to your climb so that you have your routine nailed and are used to sleeping in a sleeping bag on a hard surface.
Diamox is the prescription name for the generic drug acetazolamide. And, though acetazolamide is prescribed for the medical treatment of glaucoma, sleep apnea, epilepsy and hypertension, it’s also used to prevent altitude sickness. You should consult with your doctor before taking it.
Relax and think positive. Although not pleasant the vast majority of people suffer only mild altitude sickness. Don’t think that every headache is cerebral oedema and every cough pulmonary oedema as this is unlikely. By relaxing and enjoying the climb you are far more likely to have a trouble free experience.