What is Altitude Sickness?  Altitude sickness is a range of symptoms that can occur when someone ascends to a high altitude too rapidly, without sufficient acclimatization.  The body can adjust to the reduced air pressure at higher altitude, but only at a rate of about 300 m (1000 ft) altitude gain per day. If you ascend faster, and everybody climbing Kilimanjaro will, then you may develop altitude sickness.

There are three main forms of altitude sickness:

• AMS (Acute Mountain Sickness) is very common when climbing Kilimanjaro
• HAPE (High Altitude Pulmonary Edema) is fluid build-up in the lungs
• HACE (High Altitude Cerebral Edema) is fluid build-up in the brain

Both HAPE and HACE are potentially fatal but are thankfully extremely rare during a well-planned Kilimanjaro climb.

There is also a range of other symptoms you are likely to experience during a Kilimanjaro climb due to the altitude. They are considered normal and shouldn’t worry you:

• You breathe faster
• You are out of breath sooner
• You may wake up frequently at night
• You need to urinate a lot more often

None of those symptoms are altitude sickness.

What are the symptoms of altitude sickness?

The symptoms of AMS are headaches, loss of appetite, nausea, vomiting, sleeplessness, fatigue, dizziness. Everybody can expect to experience at least some of these symptoms in a mild form.

The most obvious symptoms for HAPE are extreme breathlessness, even at rest; rattling breath, coughing with pink froth and blue lips or finger nails.

HACE becomes apparent as a lack of coordination, inability to walk in a straight line, confusion and irrational behaviour (to the point of not acknowledging the symptoms).

How dangerous is altitude sickness? The symptoms of acute mountain sickness as described above are self-limiting and not dangerous. In fact, your guides may tell you during the briefing not to worry, that it is quite normal to be vomiting repeatedly during that last final push top the summit!

However, if you do experience symptoms, your guides should also keep monitoring you, because AMS can progress to one of the more severe forms of altitude sickness.

Who gets Altitude Sickness?

Anybody can get altitude sickness. There is no way to predict how your body will react if exposed to high altitude without proper acclimatization.  Susceptibility to altitude sickness is random. Fitness is no protection. People who are extremely fit and exercise a lot get it just as easily as beginner hikers.  Men appear to be more susceptible than women, especially young and fit men. Men will often ascend faster. Too fast. Older people seem to be less susceptible. Older people tend to ascend more slowly, and nothing protects you better from altitude sickness than ascending slowly.

When do you get Altitude Sickness? Highly susceptible people can experience symptoms from 2500m onwards. The chance of developing AMS increases with the height but the rate of altitude gain is even more important.  Mt. Kilimanjaro is 5895m high. Pretty much everybody on a Kilimanjaro climb will experience some symptoms of altitude sickness during that last push to the summit.

There are other factors that increase the likelihood of altitude sickness, apart from the absolute height itself:

• Rate at which a height is achieved (the faster you ascend the bigger the risk of developing symptoms).  This factor is more important than the absolute height itself!
• Time spent at height (symptoms start appearing within 6-10 hours though they can be delayed)
• Physical exertion
• Dehydration

Symptoms of acute mountain sickness typically take one or two days to disappear. If you keep ascending they may not go away. For most people the symptoms come and go during the day, disappear overnight, only to come back the next day as the climb continues.

AMS can be very unpleasant, but with the right preparation and at a sensible pace, most people can climb to at least the last camp below the crater rim (around 4700m). It’s that last push to the summit where AMS becomes the make it or break it issue.

How can I reduce the chances of getting Altitude Sickness?

The key to preventing altitude sickness on Kilimanjaro is taking your time. Altitude sickness is not just a result of the absolute height you are at, it also depends how fast you got there!  Even though our susceptibility to extreme altitude varies and is impossible to predict, we do know that the body adjusts to it eventually. There are many things you can do before and during a Kilimanjaro climb that will lessen the risk of altitude sickness symptoms.