airplane cabin with people sitting

4 Ways Flying Impairs Immune Function

Do you often find yourself sick or feeling off after flying? There’s a reason for that.

Air travel is extremely debilitating for your body. One of the systems that is hit the hardest is your immune system. Here are four ways that flying directly weakens your immune system and increases your risk of getting sick after that flight.

4 Ways Flying Impairs Immune Function

1. Dehydration: At just 10-20% humidity, an airplane cabin is drier than the Sahara desert! For every hour of flying, you lose 8 ounces of water. This leaves most people incredibly dehydrated. Dehydration causes digestive issues, reduces metabolism and cell function, slows blood flow, and promotes inflammation. All of these effects impair your immune system.

2. Digestive Issues: The fluctuating pressure, oxygen, and temperature in planes causes your stomach and intestines to expand. Your body also has to work harder to circulate blood to the limbs in the face of high altitude and dry air, leading to digestive issues such as gas and bloating. 80% of immune cells are located in the digestive system (gut), the cornerstone of the immune system. There is strong interplay between the gut microbiome and immune system, so when your digestive system is compromised, your immune system suffers.

3. Poor Circulation: Sitting for extended periods of time slows blood flow through the arms and legs. When the circulatory system can’t pump blood effectively to all parts of the body, there is a drop in blood, oxygen, and nutrient delivery to affected areas. Immune cells don’t flow like they should and can't defend as well against foreign pathogens. Furthermore, poor circulation can cause a range of digestive issues which further compromises your immune system.

4. Low Oxygen: Planes have lower oxygen levels than sea level as a result of the low air pressure at 35,000 feet. Research shows that these conditions impair certain immune system functions for a few days after long flights: lymphocyte responses were decreased. Lymphocytes include T cells, B cells, and natural killer cells, the primary types of white blood cells made by the immune system to combat foreign pathogens.


Your body, particularly your immune system, is severely compromised during air travel. To help combat the negative effects of flying, make sure to drink enough water, eat well, clean nearby surfaces, wash your hands regularly, and stand up and walk around periodically during a flight.

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Taking Well Traveled for an immunity boost will also provide your body with a much needed lift. Your body will thank you later!


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