On a normal day on land, the air pressure on both sides of your eardrum is equal, with air passing easily through the Eustachian tube, a narrow tube lined with membranes that connects the back of the nose to the middle ear.
Up in the air, even though you're in a pressurized cabin, the air pressure quickly becomes unequal. You can feel that change in your eardrums, which do not adapt to the pressure imbalance right away. If you don't equalize that pressure—more on how to do that in a second—then it can cause pain in your ears.
The same thing happens when you go diving, another situation with a rapid change in pressure. Underwater, pressure increases and the Eustachian tube doesn't adapt quickly enough to the change in pressure.
What can you do to ease the pain?
Dr. Carl Philpott, professor of rhinology and olfactology at Norwich Medical School at the University of East Anglia in England, encourages passengers to equalize the pressure simply by yawning or swallowing, as both help relieve the pressure by opening the Eustachian tube.
You can make your swallowing more effective by sucking something sweet, "as sucking helps encourage swallowing, which encourages the opening of the Eustachian tube," Philpott says. If babies need to pop their ears, giving them a bottle or pacifier to suck may help.
He also advises using a nasal decongestant pill or an over-the-counter nasal spray. "If you anticipate it might get bad, it would be ideal to use a decongestant just before boarding, and if it's particularly bad, then on the airplane before descending, too," he says.
Another option is to do something called the Valsalva maneuver, where you pinch your nostrils shut, gulp a mouthful of air and gently blow the air out of your nose—an action you may have to repeat several times during a descent. If you do this correctly, you should hear a popping sound as the ears unblock. "However, it is better to try yawning, swallowing or using a decongestant first, as it is harder to do the latter and more uncomfortable," Philpott says.
What happens if you don't equalize the air pressure?
Besides your ears feeling full of pressure, if you don't unblock the Eustachian tube, fluid can "seep into the area from the membranes in an attempt to overcome the vacuum," a condition known as fluid in the ear," according to the American Academy of Otolaryngology-Head and Neck Surgery. Rarely, this can lead to developing a hole in the ear drum, hearing loss or dizziness, the group's website says.
Are some people more prone to plane-related ear pain than others?
"People with active problems with swelling in ears and nose will be more adversely affected," says Philpott . This, unfortunately, includes passengers with colds. "The lining in the nose and sinuses and tubes is the same throughout, and swelling can affect all of that," he says. Children are also more prone to problems with ear pressure on airplanes. Because of the way the Eustachian tube develops, kids have a shorter, more horizontal tube than adults. That means it can't maintain a normal air pressure, or drain away mucus and other debris from the ear, as effectively.