If you get an upset, gassy stomach while traveling on planes, you’re not alone.

The average person passes gas 12 to 25 times a day, but when you’re on a plane, you might feel like you’re constantly breaking wind. In addition to feeling gassy, some may experience an increase in other stomach issues during air travel. Though scientists have yet to directly measure digestive changes in people traveling on commercial passenger airlines, high-altitude research has revealed some clues to what’s happening in the gut when you’re in flight.

As you ascend to higher altitudes, atmospheric pressure decreases. This change in pressure makes the air feel thinner because there’s less oxygen. Low air pressure and cold temperatures at these elevations cause the air to expand, spreading out molecules such as oxygen, nitrogen and argon, all necessary components of air. When the blood doesn’t carry sufficient oxygen to tissues, it causes hypoxia, says Harvey Hamilton Allen, Jr., a gastroenterologist at Digestive Disease Medicine of Central New York. A reduced oxygen level in the body slows down the activity of digestive enzymes, which may contribute to problems with digestion. Research on hypoxia has also indicated several other gastrointestinal (GI) changes, from an upset stomach to more severe issues, such as bleeding in the bowels, Allen says.

Fortunately, traveling in a plane isn’t the same as climbing to the top of Mount Everest, which stands at a lofty height of 29,029 feet. Though commercial airplanes soar a bit higher at an altitude between 31,000 and 42,000 feet, they contain cabin-pressure-control systems in which conditioned air simulates a pressure akin to that at 8,000 feet of altitude.

That change in cabin pressure can still make gas in your gut expand if you have food in your stomach. Think of how your ears pop when the plane quickly ascends or descends, says Rudolph Bedford, a gastroenterologist at Providence Saint John’s Health Center in California. Like the middle ear, the gut has air-filled cavities that widen to adjust to the sudden shift in pressure.

“Changes in cabin pressure and oxygen saturation, along with the vibration and motion of the plane, can inhibit gastric emptying,” Allen says. In other words, digested food can’t move to the small intestine, making it more difficult to do a number two. This can contribute to feeling bloated, gassy and nauseated.

The length of your flight matters as well. A one-hour flight won’t disrupt your gut as much as a 14-hour trip will. Spending most of your time sitting in a cramped seat can compress the abdomen and make it harder for food to pass through. Even if you maintain a good posture, sitting for long periods of time makes it harder for the expanded gas in the GI tract to escape. “Being less active slows down your intestinal motility, thereby exacerbating bloating and constipation,” says Sri Naveen Surapaneni, a gastroenterologist at Memorial Hermann Health System in Texas. Additionally, if you have heavy foods in your stomach, this could be problematic if the plane runs into any turbulence. Surapaneni says a bumpy ride could lead to nausea and vomiting for people prone to motion sickness.

Stress might also be a culprit in a gassy airborne stomach. Research has shown that the gut has a close relationship with the brain: people with flight anxiety release the stress hormone cortisol, which reduces blood flow and oxygen to the digestive system. The decreased blood flow, in turn, slows down the digestive system. “For many people with anxiety, getting on a plane and flying for long periods stimulates symptoms of bloating, cramping in their abdomen and the butterflies-in-their-stomach feeling,” Bedford says.

If you’re someone with a preexisting GI condition, such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD), gastroenterologists warn that flying can worsen your symptoms. Bedford says people with Crohn’s disease, a type of IBD, may have episodes of diarrhea, while people with IBS, a noninflammatory condition that causes abdominal discomfort and altered bowel movements, report frequent bloating, diarrhea and constipation. The increase in symptoms, Bedford says, is not typically caused by the flight itself but by the anxiety of flying. Flight anxiety and underlying stress from delays or unexpected changes to travel plans may cause many people’s IBS to flare up, he says.

The good news is you can take steps to prevent tummy troubles on your next flight. Gut experts recommend drinking a lot of water. “When you’re traveling, you’re usually not drinking as much, so you’re becoming dehydrated,” Allen says. The dry air and low air pressure in long flights is dehydrating. “Dehydration due to low humidity levels in the cabin can slow down digestion and worsen constipation and preexisting IBS symptoms,” Surapaneni explains. Consider bringing a refillable water bottle with you on the plane.

If you are eating before your flight, opt for a light meal that’s gentle on the stomach. This includes lean proteins and foods rich in fiber and healthy fats, such as salmon and Greek yogurt with berries. “You don’t really want to have processed foods or salty foods before getting on a flight,” Bedford says. He also encourages people to not eat at least 30 minutes before the flight. Eating earlier can help your stomach digest the food before boarding.

Once on the plane, you’re better off skipping the wine, coffee or carbonated drinks, which might worsen an already upset stomach. Surapaneni also advises to stay mobile when it’s safe to do so, whether that’s by standing up to take a stretch or walking around the cabin.

If you have a GI condition or are nervous about an upcoming flight, it’s always a good idea to consult with your doctor before boarding in case there are other remedies they would recommend. Also, don’t fret if you continue feeling some digestive issues after landing. These symptoms are temporary and usually pass in 24 to 48 hours, Bedford says.

So the next time you’re on a plane, if you’re a little gassier than usual, Bedford says, it’s better to release it rather than attempt to hold it in for an entire flight. “Move around and let it rip—hopefully not sitting next to somebody, if you can avoid it,” he adds.