Leg and foot swelling during air travel is common. It's usually harmless. The most likely reason for it is sitting for a long time without moving during a flight.

Yes, flying frequently causes a condition known as gravitational edema, characterized by swelling in the feet, ankles, and legs. This happens primarily due to inactivity and gravity; when you sit for long periods in a cramped seat, blood pools in the lower extremities because the "calf muscle pump" isn't actively pushing it back up to the heart. This effect is worsened by the lower cabin pressure and low humidity, which can cause the body to retain fluids and lead to slight dehydration, making the blood more viscous. To combat this, experts recommend wearing compression socks to support circulation and performing "seated exercises" like ankle circles or toe flexes every hour. Staying hydrated with water while avoiding alcohol and salty snacks is also crucial, as salt encourages the body to hold onto excess water. Most swelling is harmless and subsides shortly after landing once you start walking again, but if the swelling is painful or occurs in only one leg, it can be a sign of a more serious condition like Deep Vein Thrombosis (DVT).