I fly from Minnesota to Texas a few times a year and always get achy legs. A resent report found the risk of developing potentially fatal blood clots in the legs roughly triples on a flight that lasts longer than four hours. The flights I take are usually only 2 1/2 hours but by the time I factor in the time sitting for take off and landing it's about 3 1/2 hours.
Deep vein thrombosis may be harmless and will often disappear without symptoms, but in some cases the blood clots come free from blood vessels in the legs and eventually lodge in the brain, heart or lungs, causing problems ranging from breathlessness and chest pain to heart attack, stroke or death.
Researchers examined the travel records of 8755 people who frequently traveled as part of their work for large companies or organizations within a 4.4-year period. They also questioned the participants about various potential risk factors, as well as occurrences of deep vein thrombosis.
The greatest risk factor was taking a long-haul flight, with 22 of the 53 observance cases occurring within eight weeks of such a trip. The researchers estimated that one blood clot occurs for every 4656 long-haul flights taken, a rate three times higher than that for shorter flights.
Equally risky was being on a birth control pill, but even women who were not on the pill are still twice as likely as men to develop deep vein thrombosis. Overweight passengers likewise had twice the risk, while people taller than six feet were 2.5 times more likely to develop blood clots than those shorter than five feet 5 inches.
Nevertheless, lead researcher FritsRosendaal said the risks of deep vein thrombosis are not severe enough that long-haul passengers should feel the need to take blood-thinning medications. "The results of our study do not justify the use of potentially dangerous prophylaxis [treatment to prevent disease] such as anticoagulant therapy for all long haul air travelers, since this may do more harm than good," he said.