They strongly advise all patients traveling on flights of more than six hours to take some simple but necessary precautions.
A blood clot known as deep vein thrombosis can develop in the veins of the leg as a result of sitting still in a cramped position for hours on end.
In many cases these clots dissolve on their own, but they can be very dangerous if they break away and travel through the bloodstream to the lungs, where they can get stuck and cause a potentially fatal pulmonary embolism.
There is still a lot of controversy about how this kind of health problem might be caused or exacerbated by air travel, but certainly there seems to be enough evidence to cause concern for some travelers.
Whether or not there's an individual risk for deep vein thrombosis, passengers should avoid constrictive clothing around the lower extremities and waist, avoid dehydration, and engage in frequent calf muscle stretching.
Patients considered at greater risk for clots should also consider using a compression stocking and may also need to take a blood-thinning medication before the trip.
Aspirin is not recommended for the prevention of travel-related blood clots. Your doctor is the best person to advise you of your personal risk and prescribe medication to prevent clot formation if necessary.
The good news is that the risk of these clots occurring on or just after a flight is very small, about one in a million. But the risk increases on longer flights and for people who already have risk factors for blood clots. Although most experts agree that sitting still for hours and the cramped seating that's the main cause of the syndrome, some theorize that it may also have something to do with the cabin pressure or the dry atmosphere inside a plane.
Studies show that certain groups are at higher risk for blood clots. Age, obesity, recent surgery, family history of blood clots, medical conditions or disease that make a person prone to clotting can put a person at higher risk. And women who are pregnant or use contraceptive pills or hormone replacement therapy are also at higher risk.
If any of these conditions are combined with the risk factor of sitting in an immobile, cramped position for a long time, it can put a person at an even higher risk.