Is flying a health risk?

Air travel can expose you to a number of factors that can impact your health and well-being. Although most travellers won't notice any adverse effects to their health during a flight, the effects from flying may present challenges if you have certain underlying health conditions.



In 2026, flying is generally considered safe for the vast majority of people, though it does carry specific physiological risks, especially on long-haul flights. The primary concern is Deep Vein Thrombosis (DVT), where blood clots form in the legs due to prolonged immobility; this risk increases by about 26% for every two hours in the air after an initial four-hour period. Additionally, the low humidity in aircraft cabins (typically 10-20%) can cause dehydration and dry out mucous membranes, making you more susceptible to airborne viruses if social distancing isn't possible. Other risks include barotrauma (ear and sinus pain caused by pressure changes) and exposure to slightly higher levels of cosmic radiation at high altitudes, though this is only a significant concern for frequent flyers or crew. To mitigate these risks, health experts in 2026 recommend staying hydrated, avoiding excessive alcohol, and performing "seat exercises" or walking the aisle every hour to maintain circulation and prevent clot formation.

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Some recent studies do in fact suggest that traveling, especially flying, can have a negative effect on your immune system, thus making it easier for you to get sick.

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While many love the experience of travelling by flight, it can be a nightmare for others who often complain of experiencing jet lag, nausea, memory loss, or brain fog post their journey. Some studies show that even relatively mild levels of hypoxia (deficiency in oxygen) can alter our ability to think clearly.

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Low air pressure during air travel also decreases the amount of oxygen in the air. This effect is modest and generally not noticeable for healthy travelers. For patients with significant lung disease, a small decrease in available oxygen can cause significant symptoms, especially with exercise.

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The effects of flying on the human body vary from mild skin dryness to more severe problems like deafness. Flying increases the risk of catching a cold, dehydration, aging faster, reduced alertness, increased risk of diseases like cancer, fuzzy thinking, and many others.

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For best protection, you are encouraged to use supplemental oxygen above 10,000 feet MSL. At night, because vision is particularly sensitive to diminished oxygen, a prudent rule is to use supplemental oxygen when flying above 6,000 feet MSL. So, when you fly at high altitudes, supplemental oxygen is the only solution.

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At high altitudes, cerebral hypoxia triggers the upregulation of VEGF. In turn, the VEGF increases capillary permeability and contributes to cerebral edema. Note, however, that brain swelling attributable to ascent to high altitudes may occur without any associated symptoms.

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This increases the risk of ischemic stroke, which takes place when an artery in the brain becomes blocked by a blood clot. Risk of developing a clot has been found to be increased during and after air travel by many research studies. In fact, clot risk may be elevated by as much as 26% for longer flight times.

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A 2021 study shows that those without heart disease may experience a 6% increase in blood pressure during a commercial flight.

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Cardiac arrhythmia. Hypoxia and increased sympathetic activation may increase the risk of cardiac arrhythmias at high altitude2; however, the incidence of significant arrhythmias during air travel is rare.

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The air on a plane contains less oxygen than the air we normally breathe in. This leads to lower levels of oxygen in the blood. If you do not have a lung condition, the drop in oxygen is not enough that you would feel the difference.

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Air travel Airplanes can be breeding grounds for bacteria and viruses, from cramped conditions to the low humidity that characterizes the air circulating on board. Low humidity can dry out your nasal passages and irritate your throat.

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Our immune systems are sensitive to fluctuations in hormone levels, and when things are kept in delicate balances, the emotional and physical exertions of flying can be enough to trigger immune responses you don't want.

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Nerves and tension can cause muscles to tense, resulting in pain following a flight.

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Takeoff and landing are widely considered the most dangerous parts of a flight.

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It is not recommended to fly with acute intracranial hypertension because the conditions in the plane can worsen your condition and cause excruciating pain. If you have chronic or benign intracranial hypertension, you might be able to fly if your condition is under control.

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Blood clots can sometimes form in your legs during air travel because you are immobile for long periods of time, often sitting in cramped spaces with little leg room. The clinical term for this type of blood clot is deep vein thrombosis (DVT). The longer the flight, the more at risk you are for developing a clot.

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Plane travel makes jet lag worse because your body moves much faster than your brain and circadian rhythms can process the time change. Other aspects of travel can also contribute to jet lag and may make symptoms worse: Long periods of sitting on a plane. Lack of oxygen and decreased air pressure in the airplane cabin.

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The only oxygen equipment allowed on an airplane is the portable oxygen concentrator (POC). If you need oxygen in flight, you must take a portable oxygen concentrator with you, and , you must let your airline know ahead of time. They may require a doctor's letter to verify the need for the POC on the plane.

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