Why Does Flying Dehydrate You? (And 3 Tips To Prevent It)

Do you often feel gross after getting off a flight, especially after a long one? Maybe you have a slight headache, your skin might feel dry and itchy, or your lips are chapped? There is a good chance you are dehydrated. In this article, we are going to answer the common question: why does flying dehydrate you? We’ll also provide some tips to help you stay hydrated during your next flight.

Causes Of Dehydration While Flying

There are a few main reasons that answer the question, why does flying dehydrate you? These include:

Pressurized Cabin

  • Typical commercial flights cruise at altitudes between 33,000 and 42,000 feet. According to National Geographic, as altitude increases, the pressure becomes less. This is because the amount of gas molecules in the air decreases. Decreased air pressure means there is less oxygen available to breathe. Therefore, in order to breathe at such high altitudes, cabins are required to be pressurized accordingly. Airplane cabins are pressurized between 6000 and 8000 feet.
  • With the average elevation for the USA at 2500 feet., a pressurized cabin at 6000 to 8000 feet can have quite an impact on travelers used to lower elevations. Firstly, cabin air pressurized at this altitude does contain plenty of oxygen for healthy passengers and crew. However, it can lead to dehydration as passengers are used to breathing air at altitudes closer to sea level (0 feet). Cabin air, that may not be as rich in oxygen as the air you would typically breathe on Earth, will cause you to breathe deeper and more frequently. More frequent breathing increases fluid loss from your body as you exhale, this can lead to dehydration.
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Cabin Humidity

  • Humidity is the measurement of water vapor in the atmosphere. The relative humidity of your home for health and comfort should be between 40% to 50%. However, cabin air on an airplane typically has a humidity of less than 20%. Low humidity may cause you to have dry skin, eyes and a sore throat.

Tips For Staying Hydrated While Flying

Some tips to help you stay hydrated next time you travel, include:

  • Drink Water
    • The best way to do this is by bringing your own reusable water bottle. After you pass through security, the first thing you should do is fill up your stainless steel water bottle. While on the plane, flight attendants will be happy to refill your empty water bottle as well. As a recommendation, you should be drinking 8 oz or approximately 250 ml every hour.
  • Avoid Caffeine and Alcohol
    • Both alcohol and caffeine have diuretic effects. Meaning they rid the body of salt and extra fluid. This makes you go to the bathroom more than usual. When your body loses those fluids by going to the bathroom, you need to replenish them. If you are going to drink alcohol or have caffeinated drinks, have them in moderation. As a general rule, have one glass of water in between caffeinated or alcoholic beverages.
  • Bring Chapstick and Moisturizer
    • Be sure to pack your chapstick and moisturizer in your carry-on bag. You’ll have to purchase a travel-sized moisturizer (3.4 oz or 100ml) so you can get through security. Throughout the duration of the flight, moisturize your hands and face regularly, in addition to applying chapstick to your lips.


In this article, we answered the question: why does flying dehydrate you? Additionally, we provided some helpful tips to keep you hydrated next time you travel.

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Facts for this article are referenced from credible sources. For further information, please read these referenced articles from the following organizations:

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