kilimanjaro altitude sickness - Exceed Expectations Tours

Altitude sickness — also called acute mountain sickness (AMS) — is the single biggest reason climbers fail to reach Uhuru Peak. It affects roughly 75% of people who climb Kilimanjaro to some degree, and it doesn’t discriminate based on age, fitness, or experience.

The good news: altitude sickness is largely preventable with proper acclimatization, gradual ascent, and awareness. This guide explains what causes it, how to recognize the symptoms, what medications help, and the strategies our guides use to keep climbers safe.

What Causes Altitude Sickness?

At high altitude, the air pressure drops and each breath delivers less oxygen to your body. Above 2,500 metres, your body struggles to adapt to this reduced oxygen supply. When you ascend faster than your body can acclimatize, altitude sickness develops.

Kilimanjaro is particularly challenging because it’s a non-technical trek — climbers can ascend very rapidly without technical climbing skills. The summit at 5,895 metres is high enough to cause serious altitude illness in anyone.

Key Fact

Fitness does not protect against altitude sickness. Marathon runners and athletes are just as susceptible as anyone else. The only proven prevention is gradual ascent and proper acclimatization.

The Climb High, Sleep Low Principle

The single most effective strategy for preventing altitude sickness is the “climb high, sleep low” approach. This means you ascend to a higher altitude during the day, then descend to sleep at a lower altitude. This gives your body exposure to altitude while allowing it to recover overnight.

Routes like Machame, Lemosho, and Northern Circuit are designed around this principle. They include acclimatization days where you climb to a higher camp, then return to sleep lower. This is why longer routes have significantly higher summit success rates.

Route	Duration	Acclimatization Profile	Success Rate
Northern Circuit	8–9 days	Excellent	95–97%
Lemosho	7–9 days	Excellent	85–95%
Machame	6–7 days	Good	80–90%
Rongai	6–7 days	Moderate	70–85%
Marangu	5–6 days	Poor	60–75%
Shira	6–7 days	Moderate	70–80%
Umbwe	5–6 days	Poor	50–65%

The correlation between acclimatization profile and success rate is clear. Longer, gradual routes give your body time to adapt.

Symptoms of Altitude Sickness

Altitude sickness ranges from mild to life-threatening. Recognizing the symptoms early is critical — ignoring them can lead to serious complications.

Mild AMS (Acute Mountain Sickness)

Manageable

Mild AMS is common and usually manageable with rest, hydration, and acclimatization. Symptoms typically appear within 6–12 hours of arriving at a new altitude.

Headache (most common symptom)
Nausea or loss of appetite
Dizziness or lightheadedness
Fatigue and weakness
Difficulty sleeping
Shortness of breath on exertion

What to do: Rest, hydrate, take ibuprofen or paracetamol for headache, and do not ascend further until symptoms improve. If symptoms worsen, descend.

Moderate AMS

Serious

Moderate AMS requires immediate attention. Symptoms are more intense and may include vomiting, severe headache, and inability to function normally.

Severe headache not relieved by medication
Persistent vomiting
Marked dizziness or confusion
Inability to walk in a straight line
Rapid heart rate

What to do: Descend immediately. Do not ascend further. Your guide will assess whether you need medical evacuation.

Severe AMS — HAPE and HACE

Emergency

High Altitude Pulmonary Edema (HAPE) and High Altitude Cerebral Edema (HACE) are life-threatening conditions requiring immediate descent and emergency medical treatment.

HAPE symptoms:

Severe shortness of breath even at rest
Coughing up pink or white frothy fluid
Chest tightness or pain
Blue lips or fingernails
Extreme weakness

HACE symptoms:

Confusion or disorientation
Loss of coordination (ataxia)
Hallucinations
Severe drowsiness or unconsciousness
Inability to walk

What to do: Immediate descent is the only cure. Oxygen and medication may be administered by your guide. This is a medical emergency.

Diamox (Acetazolamide)

Diamox is a prescription medication commonly used to prevent and treat altitude sickness. It works by acidifying your blood, which stimulates breathing and speeds up acclimatization.

Usage	Dosage	When to Start	Notes
Prevention	125mg twice daily	24 hours before ascent	Continue until descent
Treatment	250mg twice daily	At onset of symptoms	Does not replace descent

Side effects: Increased urination, tingling in fingers and toes, altered taste (especially with carbonated drinks), and nausea. These are usually mild and temporary.

Important

Diamox is a prescription medication. Consult your doctor before your trip. It is not a substitute for proper acclimatization — it only speeds up the process. Never rely on Diamox alone to prevent altitude sickness.

Prevention Strategies

Choose a Longer Route

7 days minimum, 8 days ideal
Longer routes allow gradual acclimatization
Success rates improve dramatically

Walk Slowly

“Pole pole” — Swahili for slowly
Rushing increases altitude sickness risk
Let your body adapt at its own pace

Hydrate Constantly

Drink 3–4 litres of water daily
Dehydration worsens altitude symptoms
Check urine colour — should be pale

Eat Well

Eat even when you don’t feel hungry
Carbohydrates are easier to digest at altitude
Avoid alcohol and heavy meals

Avoid Alcohol and Sedatives

Alcohol worsens dehydration and breathing
Sleeping pills can mask symptoms
Both increase altitude sickness risk

Listen to Your Body

Don’t ignore symptoms
Tell your guide immediately
Descending is not failure — it’s safety

How Our Guides Keep You Safe

All our guides are trained in high-altitude first aid and carry pulse oximeters to monitor your oxygen saturation and heart rate daily. They use the Lake Louise Scoring System to assess altitude sickness severity.

Safety Measure	What We Do
Daily health checks	Oxygen saturation and heart rate monitored every evening
Lake Louise Scoring	Standardized assessment of AMS symptoms
Oxygen cylinders	Carried on every climb for emergencies
Stretcher evacuation	Available on all routes for rapid descent
Guide training	Wilderness first aid and altitude illness management
Descent protocol	Immediate descent if symptoms worsen

Frequently Asked Questions

Who is most at risk of altitude sickness?

Anyone can get altitude sickness, regardless of age, fitness, or experience. However, risk increases with rapid ascent, previous history of altitude sickness, and climbing above 3,000 metres without acclimatization. There is no way to predict who will be affected.

Can I climb Kilimanjaro if I’ve had altitude sickness before?

Yes, but with caution. Having had altitude sickness before increases your risk of getting it again. Choose a longer route (8–9 days), consider preventive Diamox, and ascend slowly. Consult your doctor before booking.

Does Diamox guarantee I won’t get altitude sickness?

No. Diamox speeds up acclimatization but does not prevent altitude sickness entirely. It’s most effective when combined with gradual ascent, hydration, and proper rest. Never rely on medication alone.

What happens if I get altitude sickness on the mountain?

Your guide will assess your symptoms using the Lake Louise Scoring System. For mild symptoms, you’ll rest and acclimatize. For moderate or severe symptoms, you’ll descend immediately. Our guides carry oxygen and are trained to manage emergencies.

Can I take Diamox if I’m allergic to sulfa drugs?

Diamox is a sulfonamide medication, so people with sulfa allergies may react to it. Consult your doctor — alternative medications like Dexamethasone may be appropriate. Always disclose allergies to your guide.

How much water should I drink on Kilimanjaro?

Aim for 3–4 litres per day. Dehydration mimics and worsens altitude sickness symptoms. Check your urine colour — it should be pale yellow. Clear urine means you’re well hydrated.

Does physical fitness prevent altitude sickness?

No. Fitness helps you physically handle the trek, but it does not protect against altitude sickness. Some of the fittest climbers suffer the worst symptoms. Acclimatization is the only reliable prevention.

At what altitude does altitude sickness start?

Symptoms can begin as low as 2,500 metres, but most cases occur above 3,000 metres. On Kilimanjaro, most climbers start feeling symptoms around Barranco Camp (3,950m) or Karanga Camp (4,050m).

Altitude Sickness on Kilimanjaro