What Happens to Your Body on an Airplane

‘Tis the season for travel! Whether you’re going to visit the fam in Kansas City or are off to the Cayman Islands for some R&R, you’ll be joining the more than 5 million people traveling by air sometime during the holiday season.

Now picture yourself there, at 40,000 feet, rocking out to Adele and playing Candy Crush on your iPad, trying to politely ignore your chatty seatmate. While everything might appear normal on the outside, there’s some wacky stuff going on inside you as you’re confined to a metal tube soaring above the clouds. Check this out, and you’ll never look at an airplane the same way again.

Nose

The humidity level in an airplane dips below 20 percent (compared to the average home humidity level of above 30 percent). That desert-like atmosphere can do more than simply leave you reaching for your L’Occitane. The low humidity “dries out the mucous membranes in your nose, sinuses, and throat, leaving you susceptible to infection,” Sanford Vieder, DO, medical director and founder of Lakes Urgent Care clinics in Michigan, tells Yahoo Health.

Mucous plays a key role in your immune system — it’s basically a bouncer that blocks microbes from entering the body. And if yours is dried out, viruses can squeeze on by and gain easy access.

The remedy? Guzzle water to keep your mucous membranes moist and up for the job.

Ears

Ever wonder what causes that uncomfortable ear popping during takeoff and landing? Your Eustachian tube (the canal that connects your ears to your nasal cavity and throat) is responsible for regulating pressure in your eardrums. “When there’s a rapid drop in pressure, like in a plane, it can be difficult for your Eustachian tube to process the change, which is why you experience ear pain and headaches,” Vieder explains. “A good way to unclog your ears is to drink water, because swallowing naturally uses the same muscular mechanism involved in opening the tube.”

That popping sensation can be downright dangerous if you have a cold or virus. “When you have an infection, the Eustachian tube swells and can’t open wide enough to equalize the pressure,” Vieder says. “As a result, your ear drum could rupture, causing hearing loss and chronic ear infections.” Yikes!

Even if you’re not under the weather, the noise level inside the cabin of a plane (which ranges from about 75 to 90 decibels — similar to a freight train or garbage disposal) can trigger temporary hearing loss. Making matters worse, people tend to jack up the volume on their headphones when listening to music to counteract the commotion. “Instead, use noise-canceling headphones to protect your ears,” suggests Marc Leavey, MD, primary care specialist at Mercy Medical Center in Baltimore. It can also help to book a seat toward the front of the plane — it’s quieter than the rear, where the engine is located.

Related: What’s Happening in Your Brain and Body as You Listen to Music

Tongue

If that Kind bar you grabbed preflight isn’t as yummy as usual, blame it on the Boeing — it turns out flying can dull your taste buds. What happens is that the decreased humidity levels on the plane dry out your nasopharynx (the chamber that leads from your nostrils to your olfactory bulb), compromising your sense of smell and, as a result, taste. “The plate on your nasal passageways is part and parcel of your taste sensation,” Leavey tells Yahoo Health. The effect is similar to eating while holding your nose — try it and you’ll find your lunch lacking flavor.

Teeth

If you’ve got a cavity, you might want to steer clear of the runway. “The depressurization in an aircraft can bring on a severe toothache,” Leavey says. “Decaying teeth have a chamber of pus at the root. In order to equalize the pressure, the air in that hole will expand, leading to pain.”

Skin

You know all that dry air we’ve been talking about? It can also mess with your skin. “The water in your skin’s outer layers evaporates into the air through a process called transepidermal water loss, which can exacerbate conditions like psoriasis or eczema,” says Janet Prystowsky, MD, a dermatologist in New York City. One early sign you’re in for a flare-up is itchiness — come armed with a (3-ounce or less!) stash of thick cream.

Oh, and make sure it includes SPF. “UV light passes through windows, and since you’re above cloud coverage when flying, your risk of skin damage is magnified,” L.A.-based dermatologist Tsippora Shainhouse, MD, tells Yahoo Health. “In fact, a study showed that, for pilots, exposure to UV rays during a one-hour flight was equivalent to lying in a tanning bed for 20 minutes.”

Intestines

When you fly, the atmospheric pressure in the cabin plunges below sea level. “As a result, any air you have in your stomach expands so as to normalize the pressure, which can trigger gas and discomfort,” Leavey says. Plus, many of our airport habits — scarfing down a rushed preflight meal, noshing on fried food, guzzling a soda from the beverage service cart — stress out our digestive systems. Leavey recommends leaning forward in your seat to try to, ahem, push the gas through your system. (Sorry in advance to your future seatmates!)

Related: 13 Foods That Fight Gas

Bowels

In addition, peristalsis (the internal contractions that move food through the digestive tract) slows to a snail’s pace as you ascend to higher altitudes. “That, added to dehydration and poor nutrition while traveling, leads to constipation,” Vieder points out. To keep things moving, stroll down the aisle occasionally, drink plenty of fluids, and pack fiber-rich snacks like pears and apples.

Legs

Being cramped in a 17-inch seat for hours on end in reduced cabin pressure can lead to swelling as fluid settles in your legs and feet. “This causes increased water retention in your lower leg tissue, which puts strain on the overlying skin — kind of like overfilling a water balloon,” says Prystowsky. “For most of us, this is an annoyance that makes our shoes feel too tight. But if you’re prone to lower leg swelling to begin with, the effect will be intensified, and you might break out in a red, itchy rash called stasis dermatitis.”

That’s not the only risk: Blood clots — known as deep vein thrombosis, or DVP — are also a possibility. “When you’re sitting immobile on a plane, your blood isn’t circulating efficiently,” Vieder says. Although anyone can experience one, you’re at a heightened risk if you smoke, take the birth control pill, or have a family history of blood clots. Aim to stroll down the aisle at least once per hour, jiggle your legs while sitting, and drink plenty of H2O to prevent your blood from thickening up.

Read This Next: Why You Always Seem to Want Tomato Juice on an Airplane

Let’s keep in touch! Follow Yahoo Health on Facebook, Twitter, Instagram, and Pinterest.