Patients Are Asking: Does Flying Increase My Risk for Clot?
Last Updated
May 23, 2024
Key Takeaways
The chance of getting a blood clot from traveling is small but some people have a higher risk, like those who are overweight, older, or pregnant.
To lower the risk of getting a clot when traveling by plane, experts recommend moving around every 1-2 hours and drinking lots of water.
People at higher risk may need to wear compression stockings or talk to their doctor about taking medicine to prevent blood clots.
Dr. Susan Kahn
Long-distance travel may raise your stress level, but can it also raise your risk of getting a blood clot?
To learn more, we spoke to Dr. Susan Kahn, a Professor of Medicine at McGill University and a Canada Research Chair in venous thromboembolism (VTE).
How does plane travel increase my risk of getting a blood clot?
Blood clots affect about 1-2 in 1,000 Americans per year, and the risk may double or triple after a flight that’s 4+ hours. Some studies estimate that 1 in 4,600 travelers will have a blood clot within 4 weeks of a long flight.
According to Dr. Kahn, “the risk of a travel-related blood clot is quite small, and the average traveler doesn’t need to worry about it. Billions of people travel by plane every year, and most of them don’t get a blood clot.”
However, those who already have risk factors for a clot may have a higher risk of developing travel-related VTE. These risk factors include:
Age over 40
Use of birth control pills or hormone therapy
Recent injury or surgery (within last 3 months)
Limited mobility
Pregnancy and up to 3 months after birth
A personal or family history of blood clots
Active cancer or recent cancer treatment
It’s unclear if long-distance air travel is any riskier than car or train travel, but there are factors unique to airplanes that can affect risk:
Air travelers sit in a tight space with the back of the knee pressed against the seat. The vein behind the knee is a common area for clots to form.
Immobility can raise the risk of a clot. Your seat assignment, turbulence, and other factors can make it difficult to move around easily.
Your body takes in less oxygen when the air pressure low. Some data suggest that lower oxygen levels can trigger the body’s clotting response.
Dehydration can also increase the risk of a clot. Drinking coffee or alcohol on a flight can fast-track dehydration.
Many people sleep on flights – and if you’re sleeping, you aren’t moving or hydrating.
How can I reduce my risk of getting a blood clot?
The good news is that there are several commonsense methods recommended by clinical guidelines that can help lower your risk:
Choose a bulkhead seat, try booking an aisle seat, or ask if your flight offers extra-legroom seating.
Try to move around the plane every 1-2 hours.
Avoid sleeping in awkward positions for long periods of time.
Try not to cross your legs.
Avoid wearing tight clothing.
Drink lots of water and avoid alcohol, caffeine, and sedatives.
Do some simple exercises in your seat to improve blood flow.
“For the average healthy person taking a long flight, we don’t recommend anything other than commonsense measures, like walking around the plane and staying hydrated,” explains Dr. Kahn.
Since there’s still a limited amount of data on travel-related VTE, the right course of action may be different for each person.
The Bottom Line
Travel-related blood clots are rare BUT moving around and staying hydrated are two ways to stay healthy – both in flight and on the ground. Talk to your doctor if you’re concerned about developing a blood clot while traveling.
