Altitude sickness on Kilimanjaro

At a glance

• AMS symptoms
• HACE and HAPE red flags
• Acclimatization
• Daily monitoring
• Oxygen and pulse oximetry
• When descent is required

Altitude illness is the most important health risk on Kilimanjaro. Acute Mountain Sickness can include headache with symptoms such as nausea, dizziness, fatigue or sleep disturbance. More serious conditions—high-altitude cerebral edema (HACE) and high-altitude pulmonary edema (HAPE)—are medical emergencies. Never hide symptoms to protect a summit attempt. TrekUp guides conduct daily health monitoring and use pulse oximetry as one piece of information, but a pulse oximeter does not diagnose safety by itself. Supplemental oxygen can support emergency management; it does not make continued ascent safe when descent is indicated. Gradual ascent and additional acclimatization time are beneficial. Walk slowly, maintain food and fluid intake and follow your guide’s instructions. Worsening symptoms, confusion, loss of coordination or breathing difficulty at rest require urgent action. The guide’s decision to stop an ascent or descend is a safety decision and must be respected.

Mild altitude symptoms above 3,000 m are common, expected, and not in themselves a reason to stop. Serious altitude illness is rare on Kilimanjaro but it is real, it can progress quickly, and the only reliable treatment is descent.

The purpose of this page is to help you tell the difference — and to make clear that hiding symptoms is the single most dangerous thing a climber does on this mountain.

Acute Mountain Sickness (AMS)

The common form. It is essentially a response to going up faster than your body can adapt, and most climbers experience some degree of it.

Mild AMS

Feels like a hangover you have not earned:

• Headache, often on arrival at a new camp
• Fatigue beyond what the day's walking explains
• Poor appetite, mild nausea
• Broken sleep
• Slight dizziness

What happens: normally you stop ascending, rest, hydrate, and it settles. Many people carry mild symptoms for a day or two and continue perfectly safely. Tell your guide anyway — they are tracking a trend, not a single reading.

Moderate AMS

• Headache that does not respond to simple painkillers
• Persistent nausea, vomiting
• Increasing fatigue and weakness
• Real difficulty sleeping
• Shortness of breath on mild exertion

What happens: no further ascent. Usually descent, and certainly descent if symptoms do not improve with rest at the same altitude.

Severe AMS

• Incapacitating headache
• Breathlessness at rest
• Inability to walk in a straight line
• Confusion, or an unwillingness to accept there is a problem

What happens: immediate descent, regardless of the hour or the schedule.

HAPE — High Altitude Pulmonary Oedema

Fluid accumulating in the lungs. Signs include breathlessness at rest that keeps worsening, a persistent cough that may produce frothy or pink sputum, a crackling sound when breathing, extreme fatigue, and blue-tinged lips or fingernails.

Descent is the treatment. Immediately, and as far down as possible.

HACE — High Altitude Cerebral Oedema

Swelling of the brain. Signs include severe headache unrelieved by anything, confusion or strange behaviour, loss of coordination — the classic test is whether somebody can walk heel-to-toe in a straight line — drowsiness, and eventually loss of consciousness.

A person developing HACE frequently cannot judge their own condition. This is why the decision is the guide's and not the climber's.

Descent is the treatment. Immediately.

How guides monitor you

Well-run climbs check in twice a day, morning and evening, and record the answers so a trend is visible before it becomes a problem. That typically involves asking a standard set of questions about headache, nausea, fatigue, dizziness and sleep, and often measuring pulse and blood oxygen saturation.

Two things are worth understanding about those readings. First, a single measurement means little — the trend across days is what matters. Second, oxygen saturation figures that would alarm a doctor at sea level are entirely normal at 4,600 m. Your guide is looking at the pattern, in context, alongside how you look and how you answer.

Prevention, in order of effectiveness

1. A longer itinerary. Everything else is a distant second.
2. Walking slowly, especially in the first three days.
3. Drinking three to four litres a day.
4. Eating despite the loss of appetite.
5. Climb high, sleep low — take the optional acclimatisation walks.
6. No alcohol, no sleeping tablets. Both suppress breathing.
7. Reporting symptoms honestly and early.

On medication

Some climbers take a prescription drug that assists acclimatisation. Whether it is right for you, at what dose, and whether it interacts with your other medication is a decision for a doctor who knows your history — not for an operator, and not for this page. We give no dosage guidance and you should be cautious of anyone who does.

Two general points that are not medical advice: it assists acclimatisation, it does not mask danger, and it is not a substitute for a sensible ascent profile. And if you plan to take it, trial it at home first so that any side effects appear somewhere comfortable.

What happens if you have to go down

You descend, with a guide, and the rest of your group continues. A properly staffed climb has enough assistant guides that this does not end anybody else's trip. It is planned for and it is routine.

Turning around is a decision your lead guide can make for you, and it is not negotiable. That authority is precisely what you are paying an experienced guide for.