Hours of sitting slow the calf pump, fluid pools, and joints stiffen, so you land with heavy, aching legs and swollen ankles.
Normal post-flight ache is both-sided, diffuse, and gone within a day of moving, hydrating, and sleeping. Hourly aisle walks, calf raises, water, and compression socks prevent most of it. The line that matters is symmetry: the NHS describes DVT as throbbing pain, swelling, warmth, and redness in one leg, usually calf or thigh, needing prompt medical help, and sudden breathlessness or chest pain after a flight as an emergency. Previous DVT, pregnancy, recent surgery, and clotting conditions raise the stakes.
What to do
Common questions
Why do my legs ache after long flights?
Your legs ache because they spent hours doing nothing in a cramped position. Sitting still slows the calf-muscle pump, blood and fluid pool in the lower legs, and you land with heavy, stiff, achy legs and puffy ankles; knees and hips add their own protest from being held at one angle. For most people this is mechanical and clears within a day of walking around, hydrating, and sleeping normally. Prevention on the flight itself: walk the aisle every hour or two, do seated calf raises and ankle circles, keep water intake up, and consider compression socks, which the NHS describes as helping blood circulation. Now the important distinction. Normal post-flight ache is both legs, diffuse, and improving. Deep vein thrombosis is different: the NHS lists DVT symptoms as throbbing pain in one leg, usually the calf or thigh, with swelling, warm skin, and redness, and says to get medical help as soon as possible if you think you have it, because a clot can travel to the lungs. Sudden breathlessness or chest pain after a flight is an emergency call, not a wait-and-see. Risk rises with previous DVT, pregnancy, recent surgery, and clotting conditions, so know your own list before long trips.