Altitude Illness

What is Altitude Illness?

Altitude Illness is a condition that occurs when travelling upwards in altitude at too rapid a pace. This illness can quickly turn into an emergency, as it is often ignored and shrugged off as tiredness, or lower atmospheric pressure, and most often occurs due to lack of oxygen. This illness affects everyone regardless of age, sex or physical fitness, and can occur even if you have travelled in high altitudes and never experienced it before. Altitude illness is also called acute mountain sickness (AMS) and can manifest in other, severe and more dangerous forms that may be life threatening if not treated. For this reason, Prevention of Altitude Illness is important if travelling to heights.

What are the Signs and Symptoms of Altitude Illness?

Symptoms of altitude illness usually develop between 6 and 24 hours after reaching altitudes of above 3,000 metres, and are generally likened to those of a bad hangover. They will include headaches, nausea, vomiting, dizziness, tiredness, loss of appetite and shortness of breath. These symptoms will often persist for a few days, until your body has adjusted to the height. If the symptoms are ignored, and you continue to travel upwards in altitude you may develop life-threatening conditions such as High altitude cerebral oedema (HACE), which is the swelling of the brain due to lack of oxygen.

Where am I Most at Risk for Altitude Illness?

You are at risk when climbing or travelling to areas of high altitude anywhere around the world, over 3,000 metres above sea level. You will not experience altitude sickness in planes, as they are kept at a similar pressure to ground level. For travelers backpacking, mountain climbing, or suddenly travelling to areas higher than those they are used to, altitude illness is always a possibility.

What Should I do to Prevent Altitude Illness?

The best way to prevent altitude illness is to travel to high altitudes (above 3,000m) slowly and gradually, allowing your body and lungs to adjust to the atmosphere. It’s recommended that you spend between 2-3 days going above 3,000 meters. Always avoid flying to areas of high altitudes directly, as the shock of sudden changes in the atmosphere may trigger the illness. If climbing, climb between 300 to 500m a day and have a rest day every 3 to 4 days of climbing. When traveling consider traveling with altitude medication. We have the altitude medication (Acetazolamide) at our clinic which can help prevent symptoms and allow you to adjust to higher altitudes quicker. In addition to altitude medication, we also recommend taking with you other medications that will additionally help with altitude illness such as Ibuprofen for headaches, anti-motion sickness and anti-nausea sickness medications such as Gravol. Other measures to prevent and/or minimize the symptoms of altitude illness is to ensure you are drinking enough water and to eat a high-calorie diet. Always avoid alcohol and smoking to prevent extra toll on your lungs and body. If you begin to experience symptoms, immediately stop to rest before continuing on your journey.

What Should I do if I Experience Altitude Illness?

When you first experience symptoms, always stop and rest for at least 24 to 48 hours until they have subsided completely. Never go any higher with Altitude Illness, as you risk more serious symptoms. To reduce your symptoms take headache medication, anti-sickness medication and drink plenty of water. Avoid any strenuous exercise. If you don’t feel any better after 24 hours, go down in altitude at least 500m and do not attempt to climb again until the symptoms subside completely. If your symptoms do not subside, see a doctor immediately to avoid complications such as High Altitude Cerebral Edema (HACE). Symptoms of HACE are more severe than Altitude Illness and often include a headache, nausea and vomiting, loss of coordination, confusion, hallucinations, swelling in the brain. If not treated immediately, HACE can be deadly. If HACE is suspected, immediately move to a lower altitude and seek medical attention, give the sufferer bottled oxygen and dexamethasone until you have reached a hospital.

Looking to climb a mountain? Be sure to book an appointment at ABC Travel Clinic if you are planning to travel to destinations with high altitudes. We are conveniently located on Yonge Street in Markham & border of Thornhill & North York, with convenient local onsite parking to the clinic.


National Health Service (2017). Altitude sickness information. Retrieved from:

Public Health Agency of Canada (2017). Altitude sickness publication. Retrieved from:

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