Health & safety
Altitude Sickness on Mount Kenya - Prevention & Treatment
Acute Mountain Sickness (AMS) is the single biggest risk on any Mount Kenya trek. It has nothing to do with fitness - it affects athletes and couch potatoes alike. The good news: it is almost entirely preventable with a sensible itinerary and the right knowledge.
Medical disclaimer: this guide is for informational purposes only and does not constitute medical advice. Consult a doctor before any high-altitude trek, particularly if you have a history of heart or lung conditions.
What is AMS?
Acute Mountain Sickness occurs when your body does not have enough time to adjust to lower oxygen levels at altitude. At Point Lenana (4,985 m), the air contains roughly 54% of the oxygen available at sea level. Your body responds by breathing faster, producing more red blood cells, and altering fluid balance - a process called acclimatisation. When ascent is too rapid, this process falls behind, and AMS develops.
AMS typically appears above 2,500 m but can occur lower in susceptible individuals. It is not predictable from fitness or age - a 25-year-old marathon runner can be more severely affected than a 55-year-old recreational hiker.
In its mild form, AMS is an inconvenience. In its severe forms - High-Altitude Pulmonary Edema (HAPE) and High-Altitude Cerebral Edema (HACE) - it is life-threatening. Recognising the symptoms and responding correctly is essential.
Symptoms - mild, moderate, and severe
Mild AMS
- Headache (the cardinal symptom)
- Fatigue and weakness
- Loss of appetite
- Mild nausea
- Dizziness on exertion
- Difficulty sleeping
Rest at current altitude. Do not ascend until symptoms resolve.
Moderate AMS
- Persistent, worsening headache
- Vomiting
- Severe fatigue
- Shortness of breath at rest
- Reduced coordination
- Confusion or disorientation
Descend immediately. Do not wait overnight.
Severe AMS / HAPE / HACE
- Extreme breathlessness at rest
- Persistent cough (pink frothy sputum)
- Loss of coordination (ataxia)
- Inability to walk a straight line
- Altered consciousness
- Bluish lips or fingertips
Medical emergency. Descend immediately and call for evacuation.
Prevention - how to stay ahead of AMS
1. Ascend slowly
The golden rule of altitude: never sleep more than 300-500 m higher than the previous night above 3,000 m. Our Sirimon and Chogoria itineraries are designed around this principle. The Naro Moru 3-day option violates it - which is why we caution against it for most trekkers.
2. Climb high, sleep low
Acclimatisation days involve hiking higher during the day, then returning to a lower camp to sleep. On the Sirimon Route, the acclimatisation day at Shipton's Camp (day 3) follows this principle exactly: you hike toward Kami Hut at 4,500 m+, then return to 4,200 m to sleep. This is one of the most effective acclimatisation strategies known.
3. Stay well hydrated
Dehydration at altitude accelerates AMS symptoms. Aim for 3-4 litres of water per day on trek. Avoid alcohol for the first 48 hours at altitude - it disrupts sleep quality and interferes with acclimatisation.
4. Consider Acetazolamide (Diamox)
Acetazolamide (brand name Diamox) is a prescription medication that speeds acclimatisation by stimulating faster breathing. It is effective at preventing and treating mild AMS. Typical dose is 125-250 mg twice daily, starting 24 hours before ascent. It is not a substitute for a sensible itinerary, but it is a useful adjunct. Consult your doctor before use - it has contraindications and side effects including tingling in the fingers and increased urination.
5. Spend a night at altitude before the trek
If you are flying to Kenya from a low-altitude country, consider spending a night or two in Nairobi (1,795 m) or Nanyuki (1,952 m) before starting the trek. This gives your body a head start on acclimatisation and noticeably reduces AMS incidence in our experience.
When to turn back
Descent is the only guaranteed cure for AMS. The question is not if you should descend when symptoms appear, but how quickly. Our guides are trained to assess AMS using established scoring systems and to make the call to descend when needed. Here is the framework we use on the mountain:
- Mild symptoms:Stop ascending. Rest at current altitude. Re-assess after 12-24 hours. If not improving, descend 300-500 m.
- Moderate symptoms:Descend immediately. Do not wait until morning. Improvement begins within 30 minutes of descending even 300 m.
- Severe symptoms:Emergency descent. Administer supplemental oxygen if available. Evacuate and seek medical care.
A summit is not worth a life. Point Lenana will be there next season. Our guides will always prioritise your safety over reaching the top.
Book with guides who take acclimatisation seriously
Every itinerary we build includes proper acclimatisation days. We will never rush you up the mountain to save a day. Get in touch to discuss the right route for your schedule.