High-altitude illnesses

If you plan to travel to a location 2,000 metres (4,900 feet) or higher above sea level, learn about the potential health risks so you can prepare for them.

Health risks at high altitudes

High-altitude illnesses can affect anyone, no matter your age or fitness level. At high altitudes, there is lower oxygen pressure in the air and your body may have difficulty adjusting. You may experience mild discomfort, like headaches and shortness of breath, to more serious issues, such as brain swelling, which can be life-threatening.

The risk of high-altitude illnesses increases the higher you go and the faster you climb.

Mild symptoms of high-altitude illnesses are common and will usually improve with a few days of rest. However, it’s important to recognize symptoms of more severe illness because, in some cases, it needs medical treatment as it may be life threatening.

You can prevent more serious problems by understanding the early signs of high-altitude illnesses.

Symptoms of high-altitude illnesses

The symptoms of high-altitude illnesses can start anywhere between a few hours to a few days after being at a high-altitude location.

Mild symptoms may include:

nausea
vomiting
tiredness
headache
lack of appetite
dizziness/lightheadedness

If you experience these symptoms, you should avoid going to higher elevations until they go away. Mild symptoms should improve on their own within a few days. Mild altitude illness can also be treated by easing symptoms, like using pain relievers for headaches.

If symptoms get worse while resting, it’s important to go to a lower elevation to prevent serious illness.

More serious symptoms of high-altitude illnesses can include:

weakness
confusion
drowsiness
extreme fatigue
loss of coordination
persistent or new cough
bluish colour on lips or skin (cyanosis)
shortness of breath at rest
severe shortness of breath with mild exertion

Before you leave

Talk to a healthcare provider or visit a travel health clinic preferably 6 weeks before your trip to get personalized health advice. Even if you’re short on time, it’s still worthwhile to make an appointment.

This is important if travelling to high altitudes, especially if you have any history of problems with your heart, lungs or anemia. Discuss your planned activities, any pre-existing health issues and any medications that you should consider bringing with you on your trip.

Also consider these steps before you travel:

Check the Travel Advice and Advisories for your destination, especially the “Health” section, which includes information on altitude illnesses for affected countries.
Sign up with the Registration of Canadians Abroad service so that we can reach out to you in case of an emergency at your destination or a personal emergency at home.
Purchase trip interruption and travel health insurance that covers emergency medical care related to high-altitude illnesses, as well as other risks associated with your planned activities.
- Learn more about trip interruption and travel health insurance.
Make note of the contact information for the nearest Canadian government office serving your destination(s) and for Global Affairs Canada’s 24/7 Emergency Watch and Response Centre.

While you’re away

Ascend gradually: Avoid rapid ascent to altitudes where you’ll be spending the night (sleeping altitude) that are over 3,000 metres (9,840 feet).
- Spend 2 to 3 nights when you reach 2,500-3,000 metres (8,200 – 9,840 feet) before going any higher.
- Spend an extra night for acclimatization every additional 600-900 metres (1,968 – 2,952 feet) climbed.
- Don’t increase your sleeping altitude if symptoms are worsening.
Climb high, sleep low: Altitude illnesses are usually associated with sleeping altitude rather than with the maximum altitude you reach during the day.
- Plan your trek so that you are sleeping at the lowest altitude possible.
Avoid consuming alcohol and sleep aids (sedatives) and over-exertion for the first 48 hours after arriving at a high elevation.
Drink more water as you ascend: Some symptoms of altitude illnesses can be caused by dehydration.
- Your body needs more water at higher altitudes than it does at lower ones.
Climb in groups for mutual support and safety.
Take preventative medications, as prescribed by your healthcare provider.

What to do if you feel sick:

stop ascending, rest and hydrate
descend to a lower altitude if symptoms worsen, while minimizing exertion as much as possible during descent
seek help and call for medical assistance if symptoms are severe

If you feel better and no longer have symptoms, you can travel or climb to a higher altitude.

Examples of high-altitude locations

High altitude: 2,000 to 3,500 m (6,500 to 11,500 feet)

Mexico City, Mexico
Machu Picchu, Peru
Quito, Ecuador
Dolomite Alps, Italy

Very high altitude: 3,500 to 5,500 m (11,500 to 18,000 feet)

La Paz, Bolivia
Mount Fuji, Japan
Mont Blanc, France

Extreme altitude: 5,500 m (18,000 ft) and above

Mount Aconcagua summit, Argentina
Mount Kilimanjaro summit, Tanzania
Mount Everest summit, Nepal

If you need help

Emergency consular assistance while outside Canada:

The Government of Canada is limited in the help it can provide you when you’re outside Canada.

We can:

give you contact information for nearby medical services, where possible
help you find health care professionals in case of a medical emergency
communicate with your relatives and friends
contact your insurance company or health care professional in Canada, with your permission

Examples of what we can’t do:

pay hospital or medical costs
pay for a medical evacuation, an air ambulance or other similar commercial services
make decisions about your medical care
interfere in your medical care
provide medical or legal advice

Learn more about services available at our consular offices outside Canada.

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