First, don't panic.
If you’ve ever slipped your shoes off during a long flight, you may have noticed that it's just a little bit harder to squeeze back into them on arrival. That's because it's extremely common for feet and ankles to swell — a condition technically known as “gravitational oedema”— when you fly. It’s also a typically harmless phenomenon.
The fact is, you have just been sitting too long — and all the liquids (i.e. blood) in your body have sunk to your feet. The effect should only last for a short time, and dissipates shortly after you walk off the plane.
It’s easy to alleviate or avoid foot and ankle swelling during a flight, too. Wear loose clothes (like these insanely stylish sweatpants), drink plenty of water, and make an effort to walk around the cabin every hour.
If you're stuck sitting with the seatbelt light illuminated, flex and extend your ankles, knees, and legs as much as possible. Avoid crossing your legs, and pass on the alcoholic beverages or any other sedatives.
People who exercise more frequently are less likely to experience these symptoms, while travelers who have a less active lifestyle are more likely to find their ankles or feet swollen at the end of a long-haul flight.
Swelling that does not go down after a few hours after the flight and the resumption of normal activity may be due to something more serious, such as a blood clot (also known as deep vein thrombosis). Other signs of this condition include swelling that occurs only in one leg, or is accompanied by leg pain. Seek immediate medical attention if you experience any of these symptoms.
Some travelers should seek a doctor’s advice before flying, especially those who have an increased risk of blood clots. Compression socks can help mitigate the effects, while a short-term prescription for a blood thinner can prevent clotting. In specific situations, a doctor may recommend that you not fly at all.
For the vast majority of flyers, however, swollen ankles and feet is no big deal. Get up, move around, drink water, check in with your body, and contact a doctor if necessary. And, while this may go without saying, remember that it never hurts to wear comfortable shoes.