Short answer: altitude sickness is the main health risk on Kilimanjaro, and the best protection is a slow pace on a longer route. Mild symptoms such as headache, nausea and poor appetite are common above about 3,500 metres and usually pass with rest and water. Severe symptoms, like confusion, loss of balance or breathlessness at rest, mean you must go down straight away. Kilimanjaro needs no climbing skills, but it does need preparation.
Why pace matters most
Your guides will set a deliberately slow rhythm, which they call "pole pole" (slowly, slowly). Going too fast is the most common cause of altitude problems. Above roughly 3,000 metres each breath holds less oxygen, and your body needs time to adjust its breathing, heart rate and red blood cell count. Routes that spend more nights on the mountain (7 to 9 days rather than the minimum 5 or 6) give your body that time. They have higher summit success rates and fewer serious cases of altitude sickness.
Altitude sickness symptoms
Acute Mountain Sickness (AMS) affects a large share of climbers to some degree. Watch for:
- Headache, often the first sign
- Nausea or loss of appetite
- Unusual tiredness or weakness
- Dizziness or light-headedness
- Poor sleep
In most cases these stay mild and ease with rest, water and a slower pace. Tell your guide every time, even if it seems minor.
HAPE and HACE: the dangerous forms
Two rare conditions can become life-threatening if they're ignored:
- HAPE (High Altitude Pulmonary Oedema) is fluid in the lungs. Signs include breathlessness at rest, a persistent cough and a rattling chest.
- HACE (High Altitude Cerebral Oedema) is fluid on the brain. Signs include confusion, stumbling or loss of coordination, and severe headache that doesn't respond to painkillers.
The only reliable treatment for both is immediate descent. A good crew checks every climber's blood oxygen and heart rate with a pulse oximeter at each camp. It carries emergency oxygen, and some teams also carry a portable hyperbaric (Gamow) bag.
How to prevent altitude sickness on Kilimanjaro
- Choose a longer route. An extra acclimatisation day does more than any piece of kit.
- Walk slowly from day one, even when you feel strong.
- Drink 3 to 4 litres of water a day. Dry mountain air and effort dehydrate you quickly, and dehydration can look like AMS or make it worse. Only drink water that has been boiled, filtered or treated.
- Eat, even when you're not hungry.
- Ask your doctor about acetazolamide (Diamox). It can help some people acclimatise faster, but it doesn't replace a sensible ascent profile.
- Be honest with your guide and be ready to go down if they advise it.
Sun, cold and everyday health
At altitude the UV is much stronger, and light reflected off rock and snow can burn skin and strain eyes even on cool, cloudy days. Bring high-SPF sunscreen, lip balm, UV-rated sunglasses and a wide-brimmed hat. Temperatures range from warm rainforest at the gate to well below freezing at the summit, so pack layers, waterproof outer layers and a sleeping bag rated for sub-zero nights.
Before you book: health checks, insurance and vaccinations
See your doctor before booking, especially if you have a heart, lung or blood pressure condition, are pregnant, or aren't sure about your fitness. A doctor who knows high-altitude travel can advise on medication.
Your travel insurance must cover trekking to 6,000 metres and emergency evacuation, including helicopter rescue. Many operators ask to see proof before the climb. Since 1 October 2026 Tanzania also requires every visitor to buy the government's US$44 inbound insurance. It covers basic medical emergencies only, so it doesn't replace your own policy. Details are in our insurance guide.
Tanzania asks for a yellow fever certificate only from travellers arriving from, or transiting through, a country with yellow fever risk. Routine vaccines (tetanus, typhoid, hepatitis A) and malaria prevention for the days before and after the climb are worth discussing with a travel clinic six to eight weeks ahead. See our health and vaccinations guide.
Fitness and training
You won't need ropes or climbing experience, but you will walk 5 to 8 hours a day for several days in a row, often on rocky, uneven ground. Build your cardio fitness and leg strength, and do several long hikes with a loaded daypack in the months before your trip. Wear your boots in well before the climb. Blisters are among the most common problems on the mountain, and among the easiest to prevent.
What a safe climbing crew looks like
Safety on Kilimanjaro is shared between you and your crew. Choose an operator that follows Kilimanjaro National Park (KINAPA) rules and employs licensed guides trained in wilderness first aid. Its crew should do health checks twice a day and carry oxygen and a pulse oximeter. It should also treat porters fairly, with proper pay, gear and food. The Kilimanjaro Porters Assistance Project publishes guidelines you can check an operator against. Ask any company you're considering how it handles an emergency descent, and expect a clear answer.
Frequently asked questions
At what altitude does altitude sickness start on Kilimanjaro?
Mild symptoms can start above about 2,500 to 3,000 metres and become common above 3,500 metres. On most routes that means the second or third day.
How many people get altitude sickness on Kilimanjaro?
Most climbers feel at least mild symptoms at some point, such as a headache on the higher camps. Serious cases (HAPE or HACE) are rare, especially on longer routes with good guides.
Which Kilimanjaro route is best for acclimatisation?
Longer routes that "climb high, sleep low", such as the 8-day Lemosho and the Northern Circuit. Compare them on our routes page, or read the best time to climb Kilimanjaro.