In Blog, Medical, Safety


The main concern people have when climbing Kilimanjaro is how their body will respond to high altitude.

While some routes up Kilimanjaro are inherently more difficult than others, almost all of them would be considered mere hiking trails if they were located at sea level. In fact, one of the reasons that so many visitors, even those who are inexperienced trekkers, can successfully climb the world’s tallest free-standing mountain is that the route profiles themselves are not that strenuous. For the most part, the day to day hikes and the elevation changes are mild to moderate. But high altitude is the component that changes everything. And your ability to deal with it will make or break your Kilimanjaro climb.


During your climb of Mount Kilimanjaro, you will pass through three altitude zones. These zones are:

  • High altitude 8,200 ft – 11,400 ft  (2,500 – 3,500m)
  • Very high altitude 11,400 ft – 18,000 ft  (3,500 – 5,500m)
  • Extreme altitude above 18,000 ft (5,500m)

Most people can ascend to 7,800 ft (2,400 m) without experiencing the effects of high altitude. However, as a person enters the high altitude zone these changes in air density and thus the amount of available oxygen begins to take effect.

How each person reacts to this change in oxygen saturation is unpredictable. It is not altered by the fitness level of the climber. It can also change by the day and by elevation. What effects a person one day may not affect them at all the very next day, week or month. There is also no correlation between age and gender.


In order to understand why altitude is such a big deal, it helps to know exactly what it does to your body. The short answer is that the higher you go, the less oxygen there is available.

At sea level oxygen accounts for about 21% of air and the barometric pressure is around 760 mmHg (milliliters of mercury) or 1 atm (atmosphere). As you climb the mountain the amount of oxygen in the air remains about the same up to approximately 69,000 ft. (21,000m). However, as the air density drops there is now less pressure packing the oxygen molecules together. In short, the molecules are now moving farther apart. With less air density the oxygen molecules are more widely dispersed in any given amount of air and hence less oxygen is available per breath.

When your body detects that it’s getting less oxygen than it’s used to, it makes you breathe deeper and faster in order to compensate. The heart beats faster too, to deliver more oxygen to your body.  More red blood cells are created to increase its oxygen carrying capacity. Other adaptations occur in blood acidity level, lung pressure, electrolyte levels, and fluid and salt balance. But despite these adaptations, your body is still operating at an oxygen deficiency.

Acclimatization is the term used for when the body adapts to the lower air pressure and decreased levels of oxygen. This is a gradual process that takes place over hours and days. The rate of acclimatization is different for everyone, and appears to have a genetic link. When acclimatization lags, altitude sickness, which is commonly referred to as acute mountain sickness (AMS), develops.


Most people will have a mild reaction to elevation. Below are some common symptoms of altitude sickness:

  • Headache: Throbbing, it gets worse during the night and when you wake up.
  • Loss of Appetite: No desire to eat or drink.
  • Nausea: Feeling sick to your stomach. You may also vomit.
  • Lethargic: Feeling weak and tired. In severe cases, you do not have the energy to eat, dress, or do anything.
  • Insomnia: Waking up constantly during the night or not sleeping at all.
  • Dizziness: You may feel dizzy and disoriented.

It’s impossible to tell if you’ll be susceptible to AMS before you are exposed to altitude. Therefore, it is always best to to ascend slowly to allow the body more time to adjust to the low oxygen environment. People who do not spend enough time acclimatizing to a new altitude before climbing higher increase the risk of developing altitude sickness.


The term “acclimatization line” is used to describe the point where someone’s altitude sickness symptoms begin to occur.

Let’s say, for instance, a person’s acclimatization line is 13,000 ft on day one. After trekking to this height and spending a night or two there, the body would acclimatize to that altitude and that person’s line might move to 15,000 ft. If they then ascend to under 15,000 ft they will remain asymptomatic, but if they climb to 15,500 ft they would begin to experience some mild altitude sickness symptoms.

The body can adjust to elevations beyond their acclimatization line by spending additional time there. However, if a person continues to ascend to points well beyond their acclimatization line, it is almost guaranteed that symptoms will worsen and further acclimatization will not occur. Put simply, you are climbing quicker than your body can adapt. We favor the longer routes on the mountain and use the climb high and sleep low approach whenever possible because these practices tend to be sufficient for most people to acclimatize.


Why You Should Use Trekking Poles on Kilimanjaro

Pole, pole – slowly, slowly.  You’ll hear this often on Mount Kilimanjaro, and you’d do well to take it to heart. Altitude sickness takes down marathon runners and strong, fit men in their prime. Tennis legend Martina Navratilova failed to summit. So did NFL MVP Ray Lewis. Do not underestimate the mountain.

It’s impossible to tell if you’ll be susceptible to AMS before you are exposed to altitude. Therefore, it is always best to to ascend slowly to allow the body more time to adjust to the low oxygen environment. People who do not spend enough time acclimatizing to a new altitude before climbing higher increase the risk of developing altitude sickness.

Although we can guide on all over Kilimanjaro’s routes, we focus on the longer routes because statistically they have the highest success rates. Our favorite routes are the 11 day Northern Circuit, 10 day Lemosho, and 9 day Machame. Unless you have been to high altitudes before and have acclimatized quickly, we encourage you to select one of these routes. It will reduce your chance of becoming sick due to altitude.

If you looked at the route itineraries, you would see that the distance hiked per day is quite short. The primary reason that climbing Kilimanjaro takes so long is that we are purposely slowing down the pace. In the first few days, your group may be going very slow – so slow that you might even start to mentally berate the guides for holding the group back. By the end of the climb you realize that the speed they set comes from years of experience, knowing what is best for the group’s success.

When you’re standing at Uhuru Peak, the summit of 19,341 feet above sea-level, you’ll be glad for those baby steps the guides made you take, and you’ll be living proof that altitude is an opponent that can be overcome.


At high altitude, there are requirements are an increased calorie and fluid intake. Not only are you burning calories by hiking, but simply being in a hypoxic environment uses more energy. However, there is a tendency for people to want to eat less rather than more.

Why? This is due to a few factors. One, the low air pressure means the gasses in the gut expand, making you feel bloated. Second,  at high altitude the body produces more leptin, the hormone that plays a role in appetite control. This spike in leptin corresponds to feeling satiated (full). Finally, typical symptoms of altitude sickness include losing your appetite or nausea.

A conscious effort must be made to keep eating even if you do not feel hungry. We provide copious amounts of food for our clients at every meal and encourage you to eat, eat, eat. The high carb, slow burning energy foods are designed to keep your energy levels up while also giving your body the nutrients it needs to acclimatize. It has been shown that at high altitudes, the body shifts its reliance from fat to carbs as an energy source. The theory is that this shift makes it easier for oxygen to dissolve into the blood. Thus, there’s a need for an even higher carbohydrate intake than usual.

Extra fluid intake is similarly important. Exercising in a dry climate will dehydrate you faster than normal, but you may not notice it as moisture is lost by breathing and evaporates from the skin. Drink plenty of water! We recommend 4-5 liters per day. Your urine should be light yellow or clear, and you should be urinating about six to ten times each day.


kilimanjaro night

When your body is hard at work during the day, it is crucial that it is allowed to recover overnight to be ready for the next day’s activities. It not only replenishes your muscles, but also is needed to acclimatize well to the current elevation.

Sleep at altitude can be difficult. The body automatically breathes more rapidly to maintain proper oxygenation. At the same time, it rids the body of carbon dioxide. But in order to expel too much carbon dioxide, the body then slows down breathing. The irregular breathing disrupts normal sleep patterns, resulting in less sleep overall, trouble falling asleep, and frequent awakenings throughout the night. Even the fittest people are affected by to the challenges of sleeping at altitude: Research has found that professional athletes experience shorter, poorer quality sleep at higher elevations.

If you feel sleepy when you arrive at a campsite, go ahead and take a nap. It’s good to take advantage of being tired rather than attempting to stay awake until the evening as there are no guarantees that you will feel sleepy then. Ear plugs can block out the noise of others in and around the campsite and tent. A sleep mask also helps. You might want to bring the dietary supplement melatonin, which studies have shown can cut down the amount of time needed to fall asleep at high altitude in half. Lastly, not everyone is used to camping, especially for consecutive days, so you might want to do some overnight trips at home so it’s not an entirely new experience.


Acetazolamide (Diamox) can prevent symptoms of AMS by increasing the rate at which the body acclimatizes. This is the most tried and tested drug for altitude sickness prevention and treatment. It works by increasing the amount of alkali (bicarbonate) excreted in the urine, making the blood more acidic. Acidifying the blood drives the ventilation, which is the cornerstone of acclimatization.

Studies have shown that a dose of 250mg every eight to twelve hours before and during rapid ascent to altitude results in fewer and/or less severe symptoms of acute mountain sickness (AMS). The treatment dosage is 250 mg twice a day for about three days. For prevention, use 125mg twice daily starting one day before your climb.


We are one of the few companies on the mountain that offers supplemental oxygen.

The ALTOX Personal Oxygen System supplies oxygen when you need it most, during the long, arduous summit attempt. The system uses bottled oxygen and a comfortable silicone nasal cannula to deliver measured doses of oxygen with every inhalation. This not only eliminates the symptoms of altitude sickness but also increases your chances of summiting by boosting your endurance. Read more here.



Above we have discussed things you can do on the mountain to prevent altitude sickness. However, there are things you can before you arrive in Tanzania.

The first is to train properly, getting in the best possible shape at home. We recommend at least eight weeks of training which should consist primarily of hiking, but also weight lifting and some cardiovascular exercises.

Another great way to prepare for altitude in your own home through the use of an altitude training system. Altitude training involves the exposure to an oxygen reduced environment and it is scientifically proven to reducing the symptoms of altitude sickness. Hypoxico is the world’s leading manufacturer of altitude training equipment. Their systems can simulate altitudes of up to 21,000ft/6,400m, so you can pre-acclimatize before you ever step foot on Kilimanjaro. This greatly increases the success and safety of your climb by virtually eliminating the chance of you succumbing to altitude sickness.

Peak Planet customers receive a 15% discount for Hypoxico altitude training system rentals. (For more information, please visit Hypoxico’s altitude training system rental page and email or call Brian Oestrike at 212-972-1009 x113. Brian is an experienced mountaineer and expert on the Hypoxico systems.)


Finally, we can’t stress it enough, you want to climb with a reputable Kilimanjaro company. The reason is simple – the best companies have the best guides who have been properly trained to prevent and treat altitude sickness. The guides at Peak Planet have the knowledge and tools necessary to keep you safe on the mountain.

Our safety procedures begin well before a client steps foot on the mountain. We have partnered with IFREMMONT, a European high altitude medical training organization with the most qualified high altitude doctors in the world, to co-develop our protocols. These measures were put in place to prevent altitude sickness as well as treat incidences should they arise.

The cornerstone of our safety program are the twice daily health checks that are performed to evaluate a client’s acclimatization level and degree of AMS, if any. Our guides take oxygen saturation readings, pulse rates, temperature, and listen to your heart and lungs each morning and evening. We take required steps to increase your chances of summiting while decreasing he likelihood of altitude sickness.

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