"2Blood clots are very rare with air travel, but they are not uncommon with the long-distance travel. You're talking about travel more than 4 or 5 hours."

Cardiologist Dr. Sumith Aleti with Orlando Health, says a blood clot can be 3life-threatening.

4Symptoms include swelling, pain, or5 tenderness in the legs, especially if it's in just one leg. Skin may also be red and warm to the touch.

If you have these symptoms, 6seek care immediately.

"If you delay that and if you take some time, then that blood clot may have 7broken off, and you're giving a chance to develop a blood clot in the lungs, which is more life-threatening."

To prevent blood clots on long trips, Aleti says to take breaks in the car—stop every couple of hours to 8stretch your legs. On a plane, wearing 9compression socks can help reduce swelling and improve 10blood flow11.

If you can't stand up, you can also try calf exercises while seated to keep the blood moving.

"You can do some toe lifts or heel lifts, or 12squeeze your 13calves."

Aleti says knowing your risk is also important.

You're more likely to get blood clots if there's a personal or 14family history of them, or if you have weight or 15vein problems. Those who are pregnant or recently had surgery are also at increased risk.