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Kilimanjaro Altitude Sickness

Acclimatization and Altitude Sickness on Kilimanjaro

The altitude of Mount Kilimanjaro, African continent’s highest peak is 5,895 meters (19,341 feet). Kilimanjaro presents a unique set of challenges, the most dangerous of which being altitude sickness. A significant proportion of people who climb over 9,000ft develop some symptoms relating to altitude. At Climbing Kilimanjaro, Safety is our Number one priority.

Effects of Altitude on Kilimanjaro

Kilimanjaro has become a very popular trek as it’s a way for ordinary hikers to experience a high mountain summit with no technical skill. Being what’s known as a “walk-up”, without the need for ropes and climbing gear, some people underestimate the potential for serious, life-threatening situations as a result of the altitude.

Kilimanjaro’s summit falls into the “extreme altitude” category, along with Aconcagua and Denali (Mt McKinley). Everest and K2 are “ultra” altitude, where acclimatization is impossible.

A Brief Introduction to Altitude

At the summit of Kilimanjaro there is approximately 49% less oxygen than at sea level. However, it’s not the percentage of oxygen in the air that changes, it’s the barometric pressure (air pressure) of the atmosphere that’s reduced.

The percentage of oxygen in the air is the same 20.9%, but it’s availability is reduced by the reduction in air pressure. What this means, in simple terms is that for any volume of air you breathe in, there are less molecules of oxygen available.

The reduced air pressure has other problems associated with it as well, allowing fluid to collect outside of the cells, around the brain (High Altitude Cerebral Edema) and the lungs (High Altitude Pulmonary Edema), both very serious conditions.

Altitude Sickness: What is it?

Mountain sickness has three main forms: Acute Mountain Sickness (AMS), High Altitude Cerebral Edema (HACE) and High Altitude Pulmonary Edema (HAPE). Additionally, AMS can be mild (very common and manageable with the right treatment), moderate, and severe (immediate descent necessary).

Let’s take a closer look at these conditions.

Acute Mountain Sickness

According to Dr. Peter Hackett of the Institute for Altitude Medicine, AMS can affect anyone above 6,000ft. The initial sign is usually a headache, which confusingly can also be a sign of dehydration or over-exertion. If other symptoms develop, then a diagnosis of AMS is probable.

In it’s mildest form, the symptoms can resemble that of a hangover, with nausea, headache, fatigue, and a loss of appetite. If you experience any of these symptoms it’s important to tell your guide and not simply try to push through. Mild symptoms can often be resolved with rest and adequate hydration.

If the symptoms of mild AMS start to get worse, a headache that you can’t shift, dizziness, coughing, shortness of breath, nausea and vomiting this is an indication that you are not adapting to the altitude (acclimatizing) and at this point you should descend to the last elevation that you felt “well”.

Treatments such as ibuprofen for the headache or anti-emetics for the nausea can mask worsening symptoms and should not be relied upon for continued ascent.

If a person suffering with moderate AMS ignores the symptoms pushing through to a higher elevation, there’s a risk that the condition can become severe. Severe AMS can lead to life-threatening complications (HAPE and HACE) and immediate descent is mandatory.

Symptoms can include severe headache, ataxia (lack of co-ordination, inability to walk properly, staggering), increased coughing and shortness of breath. Someone with severe AMS will likely need evacuation from the mountain either by stretcher or helicopter.

Complications resulting from severe mountain sickness are HAPE and HACE.

Basecamp MD explains that HAPE can develop as a result of the lung arteries developing excessive pressure as a result of the low oxygen environment. This pressure causes build up of fluid around the lungs.

Confusingly, it’s possible for a climber to develop HAPE even if they don’t seem to have symptoms of severe AMS.

Look out for:

  • Coughing up blood or mucus
  • Abnormal lung sounds
  • Extreme listlessness
  • Difficulty breathing
  • Lips going blue
  • Confusion, lack of coordination

Anyone at altitude who feels as though they have a respiratory infection should assume it’s HAPE until a medical professional proves it to be otherwise. If HAPE is suspected, oxygen is often administered in conjunction with immediate evacuation to a medical facility.

As oxygen levels in the blood drop, the brain can suffer from lack of oxygen, leading to HACE.

HACE is a very dangerous condition that requires immediate medical treatment. As fluid builds up around the brain, the climber comes increasingly confused, lethargic and drowsy, incapable of walking and behaving strangely.

Look out for:

  • Disorientation, confusion, hallucinations, talking nonsense
  • Lack of coordination, staggering, inability to walk
  • Irrational behavior
  • Severe headache, sometimes accompanied by nausea and vomiting

HACE cannot be treated without immediate evacuation to a medical facility.

Journey to the Top of Africa with Confidence


A trek in this mountain is a life-time awe experience, a world class achievement that we are at Smile with Us will be happy to be part of while you take on. Focus is to get you to enjoy every moment of the trek as you find your way to the top. A team of well-motivated professional guides and porters will take on the lead as you take the challenge.