A beginner's guide to high altitude & altitude sickness

Trekking at altitude should be taken seriously by everyone, even experienced hikers. Physical exertion at high altitude takes a toll on the human body, and many people experience altitude sickness while attempting to summit Kilimanjaro. Trekkers may start to experience symptoms of altitude sickness from about 2,500m, on day one of their summit trek. At this height, your risk of developing symptoms of altitude sickness increases significantly.

The most important thing you can do, is apply the golden altitude rule; do not sleep more than 500m higher than the night before once you exceed 2,500m. Applying this rule means that you should not trek Kilimanjaro in under seven days. Seven days will give you enough time to acclimatise, allowing you to avoid getting altitude sickness and significantly increasing your chance of summiting Kilimanjaro.

All about altitude sickness

Altitude sickness is caused by low oxygen levels in the air at altitudes above 2,500m. It is most likely to occur when the body has not had time to adjust to a lower oxygen intake, known as the process of acclimatising. Altitude sickness can affect anyone, even those who are young or very fit. If left untreated, altitude sickness can be fatal.

Symptoms of acute mountain sickness

The first stage of altitude sickness is acute mountain sickness. The good news is, acute mountain sickness cannot kill you and has mild symptoms. Acute mountain sickness is frequent, almost everyone trekking Kilimanjaro will have these symptoms, and relatively easy to manage. For example, it is common for a climber to experience mild headaches or nausea at the end of a day of hiking. Usually, these symptoms subside by morning and you are able to continue your ascent. 

Acute mountain sickness symptoms may include:

• Headache
• Feeling dizzy and/or weak
• Nausea or vomitting
• Poor appetite
• Sleep disturbance
• Fatigue, lethargy or breathlessness

Altitude sickness may be worse at night and can last for multiple days, even if you stay at the same altitude. Mild altitude sickness must be closely monitored because it can progress to HAPE of HACE in a matter of minutes. 

High altitude pulmonary oedema (HAPE)

Acute mountain sickness can progress, resulting in excess fluid on your lungs. When this occurs, it is known as high altitude pulmonary oedema (HAPE). HAPE can be fatal and the main symptoms include:

• Shortness of breath
• Coughing frothy saliva
• Racing heart
• Lips can turn blue in extreme cases

High altitude cerebral oedema (HAPE)

Acute mountain sickness can also progress to swelling of the brain. This is known as high altitude cerebral oedema (HACE). HACE can be fatal and the key symptoms include:

• Confusion
• Irritability
• Erratic or uncharacteristic behaviour (i.e. becoming violent, emotional or abusive)

How to avoid altitude sickness

Our team is extremely experienced, and since 2015, we’ve helped 98% of our trekkers summit Kilimanjaro. To help monitor your symptoms, we complete an altitude sickness scorecard twice daily for every trekker on Kilimanjaro. This scorecard has been developed by high altitude professionals and provides guidelines for if you should continue to ascend, stop ascending, or even descend. We also record your heart rate and oxygen stats, and we have developed safety procedures to minimise the risk and ensure you enjoy your experience. One of which is our “safety over summit” policy.

All you have to do is transparently communicate with our team so that we can help you manage your symptoms. This way, you can safely continue to the summit or if your symptoms are severe, we can quickly get you off the mountain to avoid injury or death. The last thing anyone needs is to die trying to summit a mountain; come back and do it another time instead!

During your trek, our experienced team will work with you to ensure that you are doing all of the right things while trekking Kilimanjaro. Together, we can minimise your chance of getting altitude sickness so you can successfully summit. Some of the practical steps we will help you to take to minimise the risk of altitude sickness include:

• Acclimatising. Our 7+ day treks include a full acclimatisation schedule. If you’d like to feel really prepared, you can even do other high altitude treks, like Mt Meru, in the lead-up.

• Trek high and sleep low. The Machame and Lemosho treks offer great acclimatisation because each day you trek higher than you camp that night. On day 3 - 4, you reach an altitude of 4,500m, before sleeping at a lower altitude for the next 2 nights. This is a fantastic way to acclimatise. 

• Start the climb in good health. If you have any underlying health conditions that might increase your likelihood of altitude sickness, make sure you talk to your doctor before your trip. Healthy iron levels are important, particularly for women (more below).

• Take it easy while hiking. We will help you to pace yourself so that you won’t push too hard one day and pay for it the next! The trick is to go slow so you keep your heart rate low, meaning you aren’t exerting yourself and your need for oxygen is lower. Aiming to be last to camp is a good trick. 

• Drink plenty of fluids. The more hydrated your body is, the quicker it will be able to acclimatise. Aim to drink atleast 3 litres of water each day, and try to avoid drinking a lot of alcohol and diuretics like coffee in the lead-up to your trek.

• Eat well. An early symptom of altitude sickness is a loss of appetite, but it’s important to continue fueling your body so that you have plenty of energy. It is also important to eat the right balance of carbs, protein, fats and sugars, something our chef will take care of for you with a variety of fresh, delicious and nutritious meals when you trek with Adventure Out Loud. 

• Sleep well. Our 4-season tents are extremely comfortable and our state-of-the-art mats will ensure you have a good night's sleep. If you’re not used to sleeping in a tent, we recommend you spend a few nights in one before your trek, to get used to what it feels like. This will get you accustomed to the sensations you’ll experience and help you feel more relaxed while on the mountain.

What is acclimatisation

Acclimatisation refers to the process of giving your body enough time to get used to the lack of oxygen at altitude. Our bodies are actually pretty amazing, and at altitude, our bodies will start to produce more red blood cells to help keep blood oxygenated. Ultimately, this helps you continue to exercise and breath at altitude, giving you a better chance of summiting. At a minimum, you should buy a 7 or longer day trek. This is the minimum amount of time you will need to acclimatise if you live in a low altitude environment like Australia. You can help the acclimatisation process by ensuring your iron levels are in a healthy range, and eating high iron foods before your trek.  

Choosing the right Kilimanjaro route is critical

Choosing the right Kilimanjaro route is citical for your success & safety. Here is a summary to help you out:

• Best acclimatisation trek = 10 Day Northern Circuit or 8 day Lemosho
• Shortest & cheapest trek = 7 Day Machame
• Best rainy season trek = 7 Day Rongai
• Best overall trek = 8 Day Lemosho

To find out more, read our what route is best for me when climbing Mount Kilimanjaro blog.

How to treat altitude sickness

The only cure for altitude sickness is to descend! Altitude sickness is best prevented by spending some time at the same altitude to acclimatise. Sometimes, you may need to go lower until your symptoms disappear. This is usually not an option during a Kilimanjaro trek, which is why it is crucial that you pick the right route for you before you start. Altitude sickness symptoms may also improve with rest, fluids and painkillers.

When altitude sickness affects the lungs or your brain, it is a medical emergency, as HAPE and HACE may both quickly result in death if left untreated. People with severe altitude sickness need help to descend as soon as possible. Supplemental oxygen can also help and we carry a bottle for emergencies.

Should I take altitude sickness medication when trekking Kilimanjaro?

Diamox (acetazolamide) tablets can be used to help prevent and reduce the symptoms of altitude sickness. However, they should never be used as an alternative to a gradual ascent and effective acclimatisation. It’s important that altitude medication is just one part of your strategy to cope with altitude sickness. Bear in mind that everyone’s body will react differently at altitude, and that being very fit doesn’t always mean you won’t experience altitude sickness. At Adventure Out Loud, we don’t consider altitude medication to be a must-have item for your trek, but we do find that Diamox appears to help manage altitude sickness. Diamox can also be a good back-up to bring with you, just in case you feel you need it.

When considering taking any new medication, you should always have a chat to your doctor to make sure it’s right for you and to get a medical opinion on any possible effects it might have on your body. Diamox tablets can have side effects, especially when you take them for the first time.

Does Diamox have any side effects? 

Altitude sickness medication can have some side effects including blurred vision, loss of appetite, nausea, vomiting and diarrhea, so it’s best to talk to your doctor before, especially if you have a history of reacting to medications. You should also consider the fact that acetazolamide is a mild diuretic, which means you may pee a lot. This is especially likely during your first few days on the medication, as your body adjusts to taking it. For obvious reasons, this side effect can interrupt your daytime activities, as well as your sleep. Most importantly, though, more regular urination can cause dehydration, so make sure you’re paying attention to what your body is doing, and drink an appropriate amount of water to cater to this side effect. You may also want to bring a pee bottle so you don't have to leave your tent at night. 

People with some medical conditions should not take Diamox, as it can react poorly with other medications or have harmful effects on your body. For example, people who are allergic to acetazolamide should not take the altitude sickness pill, as this is one of the key ingredients. You also should avoid taking Diamox if you have any of the following conditions:

• Kidney disease
• Liver disease
• Severe lung diseases
• Conditions requiring high-dose aspirin therapy
• Sodium or potassium disturbances

People with diabetes or glaucoma should also ensure they discuss Diamox with their doctor before taking it.

Altitude sickness fact sheet

There is a lot to learn about altitude sickness, and if you’re trekking at altitude for the first time, you won’t be able to anticipate how your body will react until you’re dong it. Adventure Out Loud can give you personalised advise in free Zoom chats prior to your trek, and consulting a travel doctor or your GP is also a great way to arm yourself with plenty of information. To help you better understand altitude sickness, we’ve developed a handy Altitude Fact Sheet. The most important thing to remember though, pick a 7+ day trek to allow yourself enough time to acclimatise.

The best way to feel prepared for your hike is to do some training beforehand. We’ve put together our picks for the best weekend hikes in each Australian capital city that will help you get ready for your Kilimanjaro trek - just see our blog. Don’t forget to pre-prepare your trekking essentials, including hiking boots and clothing so that you can wear them in while training, and you can find out more about packing for Kilimanjaro in our blog, how to pack for Mount Kilimanjaro + a complete packing list.

Kilimanjaro itinerary ideas

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For more information about trekking Mount Kilimanjaro, check out our ultimate guide to trekking Mount Kilimanjaro. Alternatively, you can book a free consultation with an African adventure experts today so we can help you plan your dream safari adventure by clicking the button below. Our private and custom-built luxury adventures are individually crafted to meet your wildest dreams! Secluded beach getaways, romantic safaris, honeymoon surprises, unique accommodation, or something a little weird and wonderful, tell us your wildest adventure dreams and we’ll make them a reality. 

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