Altitude sickness is the main reason climbers do not reach the summit of Kilimanjaro. It can affect anyone, whatever their age or fitness. The good news is that it is largely preventable with a slow pace and enough days on the mountain, and that its early signs are easy to recognise.
Why altitude affects you
As you climb, air pressure drops and each breath carries less oxygen. At Uhuru Peak, 5,895 metres, it is roughly half the amount at sea level. The body adapts by breathing faster and, over several days, making more red blood cells. If you climb faster than your body can adapt, you get sick.
Symptoms to watch for
| Condition | Signs | What happens |
|---|---|---|
| Acute mountain sickness (AMS), mild | Headache, nausea, tiredness, poor sleep, loss of appetite | Common. Rest, drink, and continue only if it eases. |
| AMS, severe | Headache that does not ease, vomiting, severe fatigue | Stop climbing. Descend if it does not improve. |
| HAPE (fluid on the lungs) | Breathlessness at rest, a cough, gurgling breath | Emergency. Descend immediately. |
| HACE (swelling of the brain) | Confusion, loss of balance, unusual behaviour | Emergency. Descend immediately. |
How to prevent it
- Choose a longer route. Seven or eight days give your body time. See how long it takes to climb Kilimanjaro.
- Walk slowly, slower than feels necessary.
- Climb high, sleep low. Routes such as Machame and Lemosho reach Lava Tower at about 4,630 metres, then descend to sleep at Barranco Camp.
- Drink three to four litres a day and keep eating.
- Avoid alcohol and sleeping pills on the mountain.
Diamox
Acetazolamide, sold as Diamox, can help the body acclimatise faster. Many climbers take it, but it is a prescription medicine with side effects and is not right for everyone. Ask your doctor before the trip.
Health checks and oxygen
Our guides check every climber twice a day, recording pulse and blood oxygen levels with a pulse oximeter and asking about symptoms. Emergency oxygen is carried on every climb. It is used to stabilise a climber who needs to descend, not to help someone continue upwards. Descent is the only real cure for serious altitude sickness.
Listen to your guide
If your guide decides you must turn back, that decision is for your safety. Read more in how hard it is to climb Kilimanjaro.
Frequently asked questions
Mild symptoms can start from around 3,000 metres, and most climbers feel some effects above 4,000 metres.
No. Climbers do not use bottled oxygen to reach the summit. Emergency oxygen is carried to help someone who becomes ill while they descend.
Many climbers do, but it is a prescription medicine. Discuss it with your doctor before you travel.
