Evidence-based fatigue guide
Altitude Sickness and Fatigue: Why High Elevations Wear You Out
Altitude sickness occurs when you travel to high elevations faster than your body can adjust to lower oxygen levels, commonly affecting hikers, skiers, and travelers above about 2,500 meters (8,000 feet). Fatigue is one of the most common symptoms, alongside headache and reduced appetite, and while most cases are mild, altitude sickness can occasionally become serious. This article covers the symptoms, prevention, and when altitude-related symptoms need urgent attention.
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Articles are researched and edited by the TiredOrSick.com Editorial Team under the direction of Dewan Md Enamul Hassan, Founder & Editor. Content is based on publicly available guidance from recognized health authorities and is intended for educational purposes. It is not a substitute for professional medical advice. Learn more about our medical review policy.
This article is for general education only. It does not diagnose conditions or replace advice from a qualified healthcare professional.
Key takeaways
- Fatigue and headache are common early symptoms of altitude sickness.
- Ascending gradually gives your body time to adjust and reduces risk.
- Fitness level does not protect against altitude sickness — anyone can be affected.
- Severe symptoms affecting the lungs or brain are medical emergencies requiring immediate descent.
Common symptoms
- Fatigue or unusual tiredness
- Headache
- Nausea or loss of appetite
- Dizziness
- Difficulty sleeping
- Shortness of breath with exertion
- A racing heart
- Mild swelling of the hands, feet, or face in some cases
Possible causes
- Reduced oxygen availability at high altitude
- Ascending too quickly for the body to adjust
- Individual variation in how quickly someone acclimatizes
- Dehydration, which can worsen symptoms at altitude
- Exertion soon after arriving at a high elevation, before acclimatizing
- Alcohol or sedative use at altitude, which can worsen symptoms
- A previous history of altitude sickness, which increases the likelihood of it recurring
Self-care guidance
These low-risk steps may help but are not a treatment plan. Speak with a healthcare professional before starting supplements or stopping medication.
- Ascend gradually, allowing time to acclimatize, especially above 2,500 meters
- Avoid alcohol and sedating medications in the first few days at altitude
- Stay well hydrated
- Avoid strenuous exercise for the first day or so after arriving at a significantly higher elevation
- Rest and avoid climbing higher if you develop symptoms, and consider descending if they do not improve
When to see your doctor
- You are planning travel to high altitude and want advice on prevention, including preventive medication
- You have had altitude sickness before and want strategies to reduce your risk
- Mild symptoms are not improving with rest and are affecting your trip
- You have an underlying health condition and are planning high-altitude travel
When to seek emergency care
Call your local emergency number or go to an emergency department immediately if you notice:
- Severe shortness of breath at rest, or a cough producing frothy or pink-tinged sputum, which can suggest fluid in the lungs (HAPE)
- Severe headache, confusion, or difficulty walking in a straight line, which can suggest brain swelling (HACE)
- Loss of consciousness
- Symptoms that worsen despite rest and do not improve, especially at higher elevations, warranting immediate descent and medical care
Frequently asked questions
How high do you have to go to get altitude sickness?
Symptoms can start above roughly 2,500 meters (about 8,000 feet), though susceptibility varies significantly between individuals, and some people notice symptoms at somewhat lower elevations.
Does being physically fit prevent altitude sickness?
No, fitness level does not protect against altitude sickness. Even very fit, young individuals can be significantly affected, since it depends on how quickly your body adjusts to lower oxygen levels, not overall fitness.
Can medication help prevent altitude sickness?
Yes, certain prescription medications can help prevent or reduce symptoms for people traveling to high altitude, and a healthcare professional can advise on whether this is appropriate for your trip.
How quickly should I ascend to avoid altitude sickness?
A common general guideline is to avoid increasing your sleeping altitude by more than about 300 to 500 meters per day once above 2,500 to 3,000 meters, with an extra rest day every so often, though individual plans should be tailored to your trip and health.
Conclusion
Fatigue and headache at high altitude are common, early warning signs that your body needs more time to adjust to reduced oxygen levels. Ascending gradually and staying hydrated can prevent many cases, but symptoms affecting breathing or mental clarity are medical emergencies that require immediate descent and urgent care.
References
Public health sources are listed in this order: USA, UK, Canada, Australia.