Altitude sickness is a common but potentially serious condition that affects people travelling to high elevations. It occurs when the body struggles to adapt to lower oxygen levels and reduced air pressure. With the right preparation, gradual ascent, and basic first aid knowledge, most cases of altitude sickness can be prevented or managed safely. Understanding the symptoms and knowing when to stop, rest or descend is essential for anyone planning a mountain or high altitude trip.
High altitude travel is increasingly popular among UK travellers, whether for trekking, mountaineering, skiing, volunteering, or visiting destinations located well above sea level. While these trips can be rewarding and memorable, they also present unique health challenges. This guide explains what altitude sickness is, why it happens, how to prevent it, and what first aid steps to take if symptoms occur. It also highlights the importance of pre travel health planning before embarking on mountain trips.
For personalised travel health advice tailored to your destination and itinerary, UK travellers are encouraged to consult Emcare Travel and Health Clinic before departure.
What Is Altitude Sickness
Altitude sickness, also known as acute mountain sickness, occurs when the body does not have enough time to adjust to reduced oxygen levels at high altitude. As altitude increases, air pressure drops and each breath delivers less oxygen to the body. This lack of oxygen can disrupt normal bodily functions and lead to a range of symptoms.
Altitude sickness typically begins at elevations above approximately 2,500 metres, although some people may experience symptoms at lower heights. The condition can affect anyone, regardless of age, fitness level, or previous experience at altitude.
Why Altitude Sickness Happens
At sea level, oxygen is readily available and easily absorbed by the lungs. As altitude increases, the amount of oxygen in the air decreases. In response, the body attempts to compensate by breathing faster and increasing heart rate. These adaptations take time.
If ascent is too rapid, the body does not have enough time to adjust. This leads to hypoxia, a state where tissues and organs receive insufficient oxygen. Hypoxia is the underlying cause of altitude sickness symptoms.
Factors that increase the risk of altitude sickness include:
- Rapid ascent to high elevation
- Flying directly to high altitude destinations
- Overexertion shortly after arrival
- Dehydration
- Alcohol consumption
- Previous history of altitude sickness
How Common Is Altitude Sickness
Altitude sickness is very common among travellers who ascend quickly to high elevations. A significant proportion of people experience mild symptoms when travelling above 3,000 metres, particularly if they do not allow time for acclimatisation.
While most cases are mild and resolve with rest, a small percentage of travellers develop more severe forms of altitude illness that require urgent medical attention. Understanding the risks and acting early greatly reduces the chance of complications.
Symptoms of Altitude Sickness
Symptoms usually develop within a few hours to one day after reaching high altitude. They may worsen during the first 24 to 48 hours if ascent continues.
Common Mild Symptoms
- Headache
- Nausea or vomiting
- Loss of appetite
- Fatigue or weakness
- Dizziness or light headedness
- Shortness of breath with exertion
- Difficulty sleeping
- General feeling of being unwell
These symptoms are often mistaken for dehydration, tiredness, or flu. However, when they appear shortly after gaining altitude, altitude sickness should be suspected.
Severe Altitude Illness
In rare cases, altitude sickness can progress to life threatening conditions. Recognising these early is critical.
High Altitude Pulmonary Oedema
This condition occurs when fluid builds up in the lungs, making breathing difficult.
Warning signs include:
- Shortness of breath at rest
- Persistent cough
- Chest tightness
- Rapid breathing
- Blue or grey lips or fingernails
- Extreme fatigue
High Altitude Cerebral Oedema
This is caused by swelling of the brain due to low oxygen levels.
Warning signs include:
- Severe headache
- Confusion or altered behaviour
- Loss of coordination
- Difficulty walking
- Slurred speech
- Drowsiness or loss of consciousness
Both conditions are medical emergencies and require immediate descent and professional medical care.
How to Prevent Altitude Sickness
Prevention is the most effective approach to altitude sickness. The key principle is allowing your body enough time to acclimatise.
Gradual Ascent
Ascending slowly is the single most important preventive measure.
General guidance includes:
- Avoid rapid ascents to high altitude
- Increase sleeping altitude gradually
- Limit altitude gains once above 2,500 metres
- Include rest or acclimatisation days every few days
- Where possible, climb high during the day and sleep lower at night
Planning your itinerary carefully reduces stress on the body and supports adaptation to altitude.
Hydration
Staying well hydrated supports circulation and oxygen delivery throughout the body. Dehydration can worsen altitude symptoms and increase fatigue.
Tips for hydration include:
- Drink water regularly throughout the day
- Avoid excessive caffeine
- Avoid alcohol during the first days at altitude
- Monitor urine colour as an indicator of hydration
Nutrition and Energy Management
At high altitude, the body uses more energy even at rest. Eating regular meals helps maintain energy levels and supports acclimatisation.
Helpful dietary tips include:
- Eat smaller, frequent meals
- Focus on carbohydrates for energy
- Avoid heavy or greasy foods
- Maintain regular meal times
Loss of appetite is common at altitude, but continuing to eat is important for recovery and adaptation.
Rest and Activity Adjustment
Physical exertion increases oxygen demand. In the first 24 to 48 hours at altitude, avoid strenuous activity.
Allow time for:
- Rest periods during the day
- Slower walking pace
- Reduced workload until acclimatisation improves
Listening to your body and pacing yourself reduces the risk of symptoms worsening.
Avoid Alcohol and Sedatives
Alcohol and sedative medications can interfere with breathing and reduce oxygen uptake. These substances also worsen dehydration and sleep disturbance.
Avoid alcohol for at least the first few days at altitude and be cautious with sleeping tablets or other sedatives unless advised by a healthcare professional.
Medication for Altitude Sickness Prevention
In some cases, prescription medication may be recommended to reduce the risk of altitude sickness. This is particularly relevant when gradual ascent is not possible due to itinerary constraints.
Medications may help:
- Improve breathing at altitude
- Speed up acclimatisation
- Reduce symptom severity
Medication should only be used following medical advice and as part of a broader prevention strategy, not as a substitute for safe ascent practices.
First Aid for Altitude Sickness
If symptoms of altitude sickness occur, early action is essential.
Stop Ascending
At the first sign of symptoms, do not continue to ascend. Continuing upward is the most common reason mild symptoms become severe.
Rest at your current altitude and monitor symptoms closely.
Rest and Monitor
Rest allows the body time to adapt. Many mild symptoms improve within 24 to 48 hours if no further ascent occurs.
Monitor for:
- Worsening headache
- Increasing nausea
- Shortness of breath at rest
- Changes in behaviour or coordination
Hydration and Symptom Relief
Drink fluids regularly and eat light meals. Simple pain relief may help manage headaches, but this should not be used to mask worsening symptoms.
If symptoms persist or worsen despite rest, further action is required.
Descend if Symptoms Do Not Improve
Descent is the most effective treatment for altitude sickness. Even a small drop in altitude can significantly improve oxygen availability.
Immediate descent is required if:
- Symptoms worsen despite rest
- Severe symptoms develop
- Signs of lung or brain involvement appear
Never ignore worsening symptoms at altitude.
Emergency Measures
In organised expeditions, additional measures may be available, such as supplemental oxygen or portable pressure chambers. These are temporary aids and do not replace descent and medical care.
Preparing for High Altitude Destinations
Some destinations present higher risk due to starting altitude or rapid elevation gain. Flying directly into high altitude cities or resorts increases the likelihood of symptoms.
Preparation should include:
- Reviewing itinerary altitude profile
- Allowing rest days on arrival
- Planning contingency days
- Knowing where medical facilities are located
- Understanding evacuation options
The Role of Pre Travel Health Advice
Altitude sickness is only one aspect of travel health planning for mountain trips. A pre travel consultation ensures your overall health needs are addressed.
Travel health professionals can:
- Assess your personal risk factors
- Advise on altitude prevention strategies
- Discuss medication options if appropriate
- Recommend relevant travel vaccinations
- Provide guidance for managing chronic conditions at altitude
UK travellers can review travel health services here.
Appointments can be booked in advance here.
Practical Tips for Mountain Travellers
- Ascend slowly and plan rest days
- Stay hydrated and eat regularly
- Avoid alcohol early in the trip
- Recognise symptoms early
- Never ascend with symptoms
- Descend promptly if symptoms worsen
These simple rules significantly reduce the risk of serious altitude illness.
Conclusion and Contact Information
Altitude sickness can affect anyone travelling to high elevations, but it is largely preventable with careful planning, gradual ascent and early response to symptoms. Understanding how altitude affects the body and knowing basic first aid steps helps keep mountain trips safe and enjoyable. For personalised advice, vaccination planning and professional guidance before high altitude travel, visit Emcare Travel and Health Clinic to begin preparing for your trip and ensure your health is fully supported before you travel.
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