Just flew from dallas to okinawa, japan. got some swelling in feet and ankles and have read that it'll go down. when should i start to be concerned?

Couple days: I would take it easy, sit with your feet elevated as much as possible today and be careful of your salt intake. The swelling should subside in a couple days. If you're on vacation, this is a little more challenging due to sightseeing and eating out. You could buy some compression stockings at a local pharmacy.

Ankle swelling: Swelling Usually resolves within 24 hours. Best to restrict salt for a few days and be sure to walk frequently to help circulation.

Edema: Keep them elevated, limit your salt and fluid intake, and compression hosiery may even be of benefit. If after 2-3 days, the swelling does not resolve, or keeps coming back, then get an evaluation. Overall, at 38, even after a long plain trip, severe swelling should not occur unless you were truly immobile for the whole trip and or are overweight possibly, so get a good check up anyway.Best wishes