Understanding High Altitude Sickness

What is High Altitude Sickness?

A Simple Explanation

Often called “mountain sickness,” this is your body’s natural response to the lower oxygen levels and decreased air pressure found at high elevations. It typically occurs above 8,000 feet (approximately 2,500 meters) and is a signal that your body needs more time to adjust to the change.

It’s Not About Fitness

One of the most common misconceptions is that altitude sickness only affects those who are out of shape. This is not true. Even world-class athletes can be severely affected. Susceptibility is highly individual and relates to your unique physiology and rate of ascent, not your level of physical fitness.

The Three Main Types

• Acute Mountain Sickness (AMS): The most frequent and mildest form. While uncomfortable, it serves as a crucial warning sign to slow down.
• High-Altitude Cerebral Edema (HACE): A severe and life-threatening progression of AMS where the brain begins to swell. It requires immediate descent.
• High-Altitude Pulmonary Edema (HAPE): A separate, life-threatening condition where fluid accumulates in the lungs. It can occur on its own or alongside AMS/HACE and also requires immediate descent.

Recognizing the Symptoms: Listen to Your Body

Mild Symptoms (Acute Mountain Sickness – AMS)

The onset of AMS often feels very similar to a common hangover. If you are at altitude and experience any of the following, assume it is AMS until proven otherwise. Please monitor yourself using this checklist:

• Headache (this is the most common and telling symptom)
• Nausea or a noticeable loss of appetite
• Fatigue, lethargy, or a feeling of weakness
• Dizziness or lightheadedness
• Difficulty sleeping or frequent waking during the night

Severe Symptoms: Do Not Ignore These

High-Altitude Cerebral Edema (HACE) – Swelling of the Brain

HACE is a medical emergency. It is a sign that mild AMS is progressing to a life-threatening state. These symptoms indicate an urgent need for descent.

• A worsening headache that does not improve with painkillers
• Loss of coordination, stumbling, or the inability to walk in a straight line (a condition called ataxia)
• Confusion, irritability, irrational behavior, or personality changes
• Extreme drowsiness or difficulty being woken up

High-Altitude Pulmonary Edema (HAPE) – Fluid in the Lungs

HAPE is also a medical emergency that can develop rapidly and can occur even if you have not experienced other AMS symptoms. Immediate descent is the primary treatment.

• Extreme shortness of breath, even when you are resting
• A persistent, dry cough that may develop into a wet, gurgling sound (sometimes producing pink, frothy sputum)
• A feeling of tightness or congestion in the chest
• A blueish tint to the lips or fingernails (known as cyanosis)
• Profound fatigue and weakness, far beyond normal tiredness

Prevention: The Golden Rules of Acclimatization

Go Up Slowly

The “Climb High, Sleep Low” Principle

This is the cornerstone of safe acclimatization. The strategy involves ascending to a new, higher altitude during the day to expose your body to the thinner air, but then returning to a lower elevation to sleep. This allows your body to rest and adapt more effectively overnight.

Recommended Ascent Rates

• Once you are above 10,000 feet (3,000 meters), you should aim to increase your sleeping elevation by no more than 1,000-1,500 feet (300-500 meters) per day.
• Plan for a rest day, with no further ascent, for every 3,000 feet (approximately 1,000 meters) of elevation gained.

Stay Hydrated and Eat Well

Water is Your Best Friend

Proper hydration is essential for acclimatization. You should aim to drink 3-4 liters of water daily. At altitude, the air is drier and you breathe faster, causing you to lose significantly more water vapor with every breath.

Avoid Alcohol and Sleeping Pills

Alcohol is a diuretic that leads to dehydration, directly hindering your body’s ability to acclimatize. Both alcohol and certain sleeping pills can suppress your respiratory drive, which is dangerous at altitude where your body needs to breathe more deeply and frequently to get enough oxygen, especially during sleep.

Carbohydrates for Energy

Your body requires more calories at altitude, and carbohydrates are the most efficient fuel source. We recommend a diet where at least 70% of your calories come from carbohydrates, as they require less oxygen to metabolize compared to fats and proteins.

Pace Yourself

Take it Easy

For the first 24 to 48 hours after arriving at a new, higher altitude, it is crucial to avoid any strenuous exercise. Allow your body time to adjust. When you walk, adopt a slow, steady, and deliberate pace. Remember that this journey is not a race; a measured pace is a sign of an experienced high-altitude traveler.

What to Do If You Feel Unwell

For Mild AMS Symptoms

• Stop Ascending: Do not go any higher. This is the most important first step. Do not attempt to “push through” the symptoms.
• Rest: Limit your activity and give your body a break.
• Hydrate: Drink plenty of water, but avoid over-hydrating.
• Pain Relief: Over-the-counter medications like ibuprofen or paracetamol can be effective for managing headaches.
• Communicate: It is absolutely vital that you inform your guide and your travel companions exactly how you are feeling. Never hide your symptoms.

If Symptoms Worsen or Don’t Improve

Descend Immediately. This is the single most effective treatment for altitude sickness. You do not need to go all the way down to sea level; a descent of just 1,000-3,000 feet (300-1,000 meters) can provide significant, and often immediate, relief.

Always follow this critical rule: If you feel unwell, assume it’s altitude sickness until proven otherwise. If symptoms are getting worse, descend.

Medication & Seeking Medical Advice

Prophylactic Medication (Prevention)

Acetazolamide (Diamox)

This is a prescription medication that can help your body acclimatize more rapidly. It is important to understand that it is a preventative measure, not a cure for existing altitude sickness, nor is it a substitute for a slow and sensible ascent. Common side effects can include a tingling sensation in the fingers and toes and increased urination.

Consult Your Doctor

CRITICAL: We are not medical professionals and cannot provide medical advice. It is essential that you consult your personal physician well before your trip. Discuss your itinerary, your personal health history, any pre-existing conditions, and whether a preventative medication like Acetazolamide is appropriate for you.

When to Seek Immediate Medical Help

Your guide is trained to recognize severe symptoms, but your awareness is key. Seek immediate help and prepare for descent if you or anyone in your group exhibits any of the clear red flags mentioned earlier:

• Any signs of HACE (confusion, stumbling, loss of coordination) or HAPE (severe shortness of breath at rest, a wet cough).
• If mild AMS symptoms do not improve with rest and hydration after 24-48 hours.
• If symptoms continue to worsen even after you have stopped ascending.