Mya Care Blogger 28 Sep 2023

It is the dream of many adventurers to hike to the top of the world’s tallest mountains and triumphantly embrace a truly life-changing perspective. However, the journey does not begin at the foot of the mountain. It requires much preparation before one is ready to make the great ascent.

Hiking to such great heights is not the same as the average mountain climb. The effects of altitude create an entirely different environment that changes many physical requirements, including fitness, blood dynamics, oxygen levels, and more.

In this article, we will cover the essential physical changes and possible risks that can happen when climbing Kilimanjaro, as well as medical tests and tips to help you prepare the best. While we refer to Kilimanjaro in this blog, the content also applies to other tall mountains.

The information in this article is for general educational and informational purposes only. Always consult your doctor or other qualified health provider for professional medical advice before embarking on a long hike.

Altitude Sickness

When preparing for climbing Kilimanjaro, one of the first things to check is your risk of contracting altitude sickness. Climbers at high altitudes may experience altitude sickness, commonly known as acute mountain sickness (AMS), which can be fatal. It occurs when your body does not adjust to the lower air pressure and decreased oxygen levels at elevations more than 2500m above sea level.

Acute Mountain Sickness is preventable and does not usually require emergency treatment. Symptoms can take 4 - 12 hours to present and include headaches, hyperventilation, nausea, vomiting, dizziness, insomnia and fatigue.

If you develop altitude sickness or come down with symptoms on the mountain, it is best to stay at the same altitude until your symptoms resolve. If they do not resolve and get worse, you may need to descend and abandon the trip.

Severe Mountain Sickness. High-altitude cerebral edema and pulmonary edema are more severe manifestations of altitude sickness that require immediate emergency medical attention.

Severe manifestations can sometimes take up to 5 days to present themselves. Symptoms of HACE include ataxia or loss of consciousness, while those of HAPE include shortness of breath at rest, debilitating fatigue, and a persistent cough that does not go away. It is important to tell your guide when you experience symptoms and what they are.

Assessing Altitude Sickness Risk

Even though acute mountain sickness may be treatable on the mountain, it is still advisable to assess your risk and work with your health so you can make the most of the experience.

Pulse Oximetry is a non-invasive test to measure your blood oxygen levels. It can help assess your susceptibility to altitude sickness and offer a clue as to whether you will develop severe forms or not. If your risk is high, it is advisable to opt for more comprehensive tests such as a High Altitude Simulation Test (HAST) or an arterial blood gas analysis.

A High-Altitude Simulation Test (HAST) gives you a rough idea of what it might be like to enter an altitude of 2500m above sea level (8000ft). A respiratory specialist will administer air with gas concentrations that mimic high altitudes and assess your responses.[1] The test is not meant to show how you would respond to the peak altitude you intend to reach, as this requires time and acclimatization to avoid serious side effects.

An Arterial Blood Gas Analysis can give insight into the composition of gases in your blood as well as the pH. This can help to assess whether your body is capable of adjusting or not and indicates how much O2 you can take in, how much CO2 you can get rid of, and how well your kidneys can cope with changes in CO2 levels (as measured via blood pH fluctuations).[2]

If you have a clear medical history, you may want to redo altitude sickness tests after reaching your peak fitness level to re-assess whether you are still at risk or not.

Precautions for High Altitude Hiking: How to Prevent Altitude Sickness on Kilimanjaro

The risk for altitude sickness increases for individuals with health problems that do not give their bodies enough time to acclimatize. Conserving one’s energy and acclimatizing are important when trying to avoid altitude sickness while scaling Kilimanjaro and other similar terrain.

You can better prevent altitude sickness by taking the below precautions[3]:

  • Improve Cardiorespiratory Fitness. At the top of Everest (8400m above sea level), the lower air pressure only allows for a blood oxygen saturation of approximately 50%. You need to be sure that you have enough blood cells and that your lungs are in top condition to sustain breathing during the hike. Physical fitness levels do not offset the risk of acquiring altitude sickness, although being fitter may help improve blood oxygenation and physical coping ability at higher altitudes.
  • Take It Slow. It is beneficial to plan a slower route up the mountain that allows for sufficient acclimatization breaks between different altitudes. According to studies, athletes may be more vulnerable to altitude sickness than the general population because they tend to push themselves harder and move too quickly up the mountain.[4]
  • Keep Medications Handy. If your risk proves to be high, but you are in good physical health and able to climb the mountain, you may want to ask your doctor for medications that can protect against mild altitude sickness. These include steroids such as acetazolamide (Diamox), dexamethasone, painkillers, and others. Speak to your doctor about which medications will be the best to bring along for the journey.
  • Maintain Energy Levels. It is important to consume a high-energy diet and to keep blood glucose levels constant when hiking Kilimanjaro or another tall summit. Consuming a diet high in carbohydrates can help to increase blood oxygenation by as much as 4%, provided one eats every 2-3 hours.
  • Keep Hydrated. Water is another form of oxygen that may prove useful on the mountain. Despite there being little to no evidence to support hydration for preventing altitude sickness, drinking lots of water may be able to help keep blood volume and pH regular, as well as support both lung and kidney function.

Can Women Climb Kilimanjaro?

Due to its latitude, Kilimanjaro is regarded as the tallest peak in the world, with the easiest ascent. Many women have managed to successfully hike Kilimanjaro without any problems. Studies are contradictory, with some showing that women may be at a slightly higher risk for altitude sickness than men, yet not others.

Can Older Adults and the Elderly Climb Kilimanjaro?

There is no maximum age for hiking up Kilimanjaro. Older adults may have a lesser risk for developing altitude sickness than younger individuals, yet may struggle with being physically able. Those in a fit enough condition can easily make the trek.

Physical Examination

Before starting a Kilimanjaro climb, it is crucial to have a complete physical assessment done by a medical specialist. This examination aims to identify any underlying health issues that might jeopardize your safety during the trek, as well as to ascertain whether you are physically fit enough for the challenge. You may need to undergo a physical examination several times during your training program before you are ready.

Body Composition Testing. It can also be useful to include a body composition test in this examination to assess all the factors contributing to your overall weight. As one scales up the mountain, rapid weight loss of 15% or more is possible, particularly as one reaches 5000m or more above sea level. You will need to build a decent amount of muscle to prepare for the journey, as you may lose muscle mass near the top of the mountain.

Conditions That May Prevent You from Hiking

Some medical conditions may disqualify you from climbing Kilimanjaro. These include:

  • Any condition that prevents you from training or becoming physically fit
  • Sarcopenia, cachexia, and other muscle-wasting diseases
  • Severe cardiovascular issues
  • Anemia
  • Uncontrolled high blood pressure
  • Respiratory disorders, including sleep apnea and acute respiratory distress syndrome
  • Prior traumatic brain injury
  • Musculoskeletal disorders

It is crucial to be transparent about your medical history to receive appropriate medical clearance, or you may put your life at risk.

Heart Health

Climbing Kilimanjaro requires a strong cardiovascular system due to the physical demands of high-altitude hiking. Poor heart health can increase your risk of altitude sickness and other complications.

Recommended Tests

Resting heart rate is ordinarily assessed before high-altitude hiking trips. If found to be over 100, a doctor’s permission may be required to go, and special considerations may be needed.[5]

Electrocardiograms (ECG or EKG) and stress tests can also help assess your heart's condition and its ability to handle the strenuous climb. These are especially helpful for climbing mountains taller or steeper than Kilimanjaro. Your healthcare provider will interpret the results to ensure your heart is up for the challenge.

Can You Climb Kilimanjaro with High Blood Pressure?

While having high blood pressure does not necessarily disqualify you from the climb, it is essential that it is well-managed and under control. To determine if your blood pressure is at a safe level for the expedition, speak with your healthcare provider.

Respiratory Health

High altitudes can put a significant strain on your respiratory system that prevents your lungs from taking in as much oxygen. Climbing Kilimanjaro may reduce your oxygen uptake to 60% when nearing the summit (over 5000m). This typically increases the tendency to hyperventilate, as does physical exertion.

Recommended Tests

Despite these changes, respiratory tests are likely only required for individuals with compromised lung health to assess whether they are fit enough.

Spirometry, a lung function test, can assess your lung capacity and function. This test can help detect any respiratory issues that might hinder your climb.

Those with lung diseases may still be able to make the climb up Kilimanjaro if they can improve their cardiorespiratory fitness[6]. However, it may be less advisable to attempt steeper climbs, such as Everest.

Mental Health

It can be mentally taxing to climb Kilimanjaro in addition to being physically challenging. As the brain consumes 20% of total body oxygen, hikers that frequent great altitudes are known to be subject to reduced mental capacity that can lead to increased anxiety and other difficulties that might get in the way of the climb.

For climbing Kilimanjaro, a lower mental reserve might promote a loss of physical coordination and speed, affecting one’s ability to scale the mountain.

At higher altitudes, memory loss and other intellectual abilities may become impaired, and oxygen deprivation can eventually lead to brain lesions, atrophy, and strokes. These are indicative of cerebral edema, a severe form of altitude sickness.

Recommended Tests

Consider undergoing a stress test to see if you are resilient enough to make the journey. Consult with a mental health professional before your climb. They can provide strategies to cope with stress, anxiety, and the psychological challenges you might face on the mountain.


Climbing Kilimanjaro is an incredible adventure, but you need to ensure your body and mind is able to handle it before embarking on the journey. You need to prepare both mentally and physically if you want to benefit the most from this experience. Before embarking on your Kilimanjaro climb, consult with a healthcare professional who specializes in travel medicine. Depending on your level of fitness and health, they can offer you individualized advice. Along with the required preparations to reduce the danger of altitude sickness, it is crucial to let the hiking company know about any health restrictions you may have.

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