Altitude sickness

What to Know Before You Travel

Travelling to high‑altitude regions can be breathtaking in more ways than one. The scenery is extraordinary, but the sudden drop in oxygen levels places real demands on the body. Understanding how altitude affects your heart, circulation, sleep, energy, and overall physiology helps you travel safely and recover well. Be prepared know your body and know  about this condition before going to visit places of altitude. I believe the clue often lies in our genetics.  Please discuss this if you are visiting these areas with your practitioner of choice.  We usually suggest an appointment 7-10 days before your trip to discuss a plan for these areas. 

Who Needs To Be Extra Careful With High Altitude Areas

If you have a heart condition, a history of clotting, or a family history of cardiovascular issues, be particularly mindful when visiting high‑altitude areas — especially if you plan to hike, climb, or exercise. Lower oxygen levels increase the workload on the heart, and the combination of exertion plus altitude can challenge the cardiovascular system more than people expect. My interest in this begins with my own prothrombin variant clotting tendency. This is just one of many that can run in a family. 

People that have other family members prone to altitude sickness. 

People with previous DVT, pulmonary embolism, arrhythmias, or reduced cardiac output should take extra care and consider slower ascent, rest days, and medical guidance before travel.

Why Altitude Illness Happens

Altitude sickness (acute mountain sickness, AMS) occurs when you ascend faster than your body can adapt to reduced oxygen pressure. At altitude, the air contains the same percentage of oxygen, but the partial pressure is lower — meaning each breath delivers less oxygen to your tissues.

Your body responds by increasing breathing rate, heart rate, and producing more red blood cells. These changes take time. When ascent is too rapid, symptoms appear because the brain and body are temporarily oxygen‑deprived.

Even very fit young people can experience altitude illness. Fitness does not protect against low oxygen; acclimatisation is what helps.  Go up to an area and spend time here before ascending to the next height. Many of us get straight up to the top point,  and may even start their hike ( exercise),  and bang they have altitude sickness. 

Common Symptoms (Mild to Moderate)

Mild altitude sickness can feel surprisingly similar to a hangover. Symptoms may include:

• Headaches

• Nausea

• Appetite loss

• Dizziness or light‑headedness

• Fatigue even when rested

• Disrupted sleep or insomnia

These symptoms indicate your body is working hard to adapt. Many travellers experience sleep disruption due to periodic breathing — a pattern of alternating deep breaths and pauses caused by low oxygen.

Most mild symptoms improve with rest, hydration, and descended altitude.  

Altitude increases cardiovascular strain. As oxygen levels drop, the heart must pump harder to deliver oxygen to tissues. Over time, the body increases red blood cell production, which can thicken the blood and increase viscosity.

This can lead to:

• Palpitations, AF

• Chest pressure

• Shortness of breath on exertion

For people with clotting tendencies, thicker blood plus dehydration plus exertion can increase risk of deep vein thrombosis (DVT).

If your calves swell, become painful, or you cannot comfortably place your foot on the ground, this should be checked by a medical professional immediately.

Severe Symptoms to Watch For

Severe altitude illness requires medical attention. Symptoms may include:

• Shortness of breath even at rest

• Confusion, irritability, or unusual behaviour

• Loss of balance or coordination

• Persistent dry cough

• Blue lips or grey skin (cyanosis)

•  

These symptoms may indicate high‑altitude cerebral edema (HACE) or high‑altitude pulmonary edema (HAPE) — both medical emergencies. Immediate descent is essential.

Clammy Skin & Other Signs

Clammy skin can occur when the body is under stress from altitude. It often accompanies dizziness, nausea, or sudden fatigue. It may indicate the body is struggling to maintain adequate oxygenation or circulation.

Altitude & Uric Acid: Gout Risk

Altitude can increase uric acid levels in susceptible individuals. Hypoxia (low oxygen) alters kidney handling of uric acid, and dehydration — common at altitude — further concentrates uric acid in the blood.

This can trigger gout symptoms even in people who have never experienced gout before.

Travellers with a history of gout should hydrate well, avoid alcohol, and ascend gradually.

Reference List 

1. Basnyat, B., & Murdoch, D. R. (2003). High-altitude illness. The Lancet, 361(9373), 1967–1974.

2. Hackett, P. H., & Roach, R. C. (2001). High-altitude illness. New England Journal of Medicine, 345(2), 107–114.

3. Luks, A. M., Swenson, E. R., & Bärtsch, P. (2017). Acute high-altitude sickness. European Respiratory Review, 26(143), 160096.

4. West, J. B. (2012). High-altitude medicine. American Journal of Respiratory and Critical Care Medicine, 186(12), 1229–1237.

5. Imray, C., Wright, A., Subudhi, A., & Roach, R. (2010). Acute mountain sickness: pathophysiology, prevention, and treatment. Progress in Cardiovascular Diseases, 52(6), 467–484.

6. Bärtsch, P., & Swenson, E. R. (2013). Acute high-altitude illnesses. New England Journal of Medicine, 368(24), 2294–2302.

7. Johnson, P. L., Edwards, N., & Burgess, K. R. (2010). Sleep at high altitude. High Altitude Medicine & Biology, 11(2), 109–116.

8. Hultgren, H. (1997). High Altitude Medicine. Stanford University Press.

9. MacInnis, M. J., & Koehle, M. S. (2016). Ventilation and oxygenation at altitude. Frontiers in Physiology, 7, 1–12.

10. Saito, H., et al. (1989). Uric acid metabolism at high altitude. Journal of Applied Physiology, 66(2), 693–697.