Flying with deep vein thrombosis

Flying and Blood Clots: Safety, Risks, Prevention, and More

There are several steps you can take to help reduce your risk for blood clots while flying.

Prior to liftoff

Based on your health history, your doctor may recommend medical treatments to decrease your risk. These include taking a blood thinner, either orally or via injection, one-to-two hours prior to flight time.

If you are able to choose your seat before the flight, select an aisle or bulkhead seat, or pay an additional fee for a seat with extra leg room. That will help you stretch out and move around during the flight.

It’s also important to alert the airline that you are prone to blood clots and need to be able to move around the plane. Let them know prior to boarding the plane, either by calling the airline ahead of time or alerting the ground crew in the boarding area.

During the flight

During the flight, you’ll want to move around as much as possible and stay hydrated. Reiterate your need to move around freely to your flight attendant, and walk up and down the aisle for a few minutes every hour as permitted. If there’s a lot of turbulence or it’s otherwise unsafe to walk up and down the aisles, there are exercises you can do in your seat to help keep your blood flowing:

  • Slide your feet back and forth along the floor to help stretch out your thigh muscles.
  • Alternate pushing your heels and toes into the ground. This helps flex the calf muscles.
  • Alternate curling and spreading your toes to improve circulation.

You can also bring a tennis or lacrosse ball on board with you to use to massage your leg muscles. Gently push the ball into your thigh and roll it up and down your leg. Alternatively, you can place the ball under your leg and move your leg over the ball to massage the muscles.

Other things you can do include:

  • Avoid crossing your legs, which can reduce blood circulation.
  • Wear loose, non-constricting clothing.
  • Wear compression stockings if you’re at increased risk for venous thromboembolism (VTE). The stockings stimulate circulation and prevent blood from pooling.

Preventing blood clots during other forms of travel

Whether it’s in the air or on the ground, long periods of time spent in a confined space may increase your risk of blood clots.

  • If you are traveling by car, plan scheduled breaks to stretch your legs or take short walks.
  • If you are on a bus or train, standing, stretching, and walking in the aisles can help. You can also walk in place at your seat if you have enough room, or take a few minutes in the lavatory to stretch your legs or walk in place.

How to tell if you’re getting a blood clot while flying

Aside from delays and annoying passenger antics, most flights go off without a hitch. But, on occasion, you might find yourself on a flight where a fellow traveler has a medical emergency. That’s what happened on a 2016 American Airlines flight from Honolulu (HNL) when Brittany Oswell suffered a pulmonary embolism, more commonly called a blood clot.

Sadly, she died from the incident. And incredibly, she’s not alone.

According to the National Blood Clot Alliance, an average of 274 people die from blood clots every day and 600,000 nonfatal blood clots occur every year. Air travel can increase this risk as you’re sitting for long periods with little room to move your legs. This can cause a particular type of blood clot called deep vein thrombosis (DVT).

Sitting in the same position for a long time, like on an airplane, can be detrimental to your health. (Photo by Tang Ming Tung / Getty Images)

“DVT’s are more likely to form when there is venous stasis, which means that the blood is pooling in the veins,” Dr. Mehmet Oz (of “The Dr. Oz Show”) told The Points Guy. “This is more likely to happen in people who are sedentary for long periods, like on a long plane ride, because part of the way the blood in the leg veins gets back up to the heart is when muscles contract.”

In 2018, Dr. Rajiv Narula, MD — founder of the International Travel Health Consultants — told TPG that “on flights more than eight hours, increased risk of DVT.” And certain studies say this condition can occur on flights as short as four hours.

While the condition can resolve itself, in some cases people experience a pulmonary embolism: when the clot travels to the lungs and blocks blood flow there. The blocked blood flow in the lung prevents the body from getting oxygen.

So, how can you tell if you have a blood clot on a plane? We chatted with a couple of experts to learn the symptoms, find out who is most susceptible and what to do if you develop one during a flight.

Related: It’s flu season — Here’s how to avoid getting sick on a plane

Know if you’re at risk

According to Dr. Narula, travelers with certain “underlying medical issues” are typically more prone to DVT.

Several factors can make a person more susceptible to developing a blood clot. “Things that put you at risk for blood clots include certain genetic clotting disorders, being immobilized because of surgery or injury, chronic diseases like heart failure and cancer, smoking and older age,” said Dr. Oz.

Different thing can cause blood clots depending on your demographic. (Photo by Scottshotz / Getty Images)

Dr. Nathan Favini, medical lead at Forward, a new technology-based healthcare startup, added that oral birth control pills and pregnancy also make a blood clot more likely. “Estrogen is thought to be the cause,” he said. “So, forms of birth control that don’t contain estrogen, like IUDs, are safer in this regard.”

If you fall into one of these categories, you should take extra precautions to help prevent blood clots and be aware if you start to develop any symptoms.

Related: What happens if you get sick during a flight?

Symptoms of a blood clot

Knowing you have a blood clot can be tricky, as you can often write off the symptoms as something else, but there are a few key warning signs to pay attention to when traveling. If you experience these symptoms, you should seek medical help immediately.

“If you develop pain, tenderness, swelling, warmth and/or redness in your legs during a flight, those may be signs of a deep vein thrombosis or blood clot,” said Favini. “If you have more than one or many of those symptoms, it becomes more likely that you’re experiencing a clot.”

When former TPG social media director, Lindsey Campbell, developed a blood clot during a six-hour flight home from Iceland, she woke up with sore and aching calves, and felt dizzy, hot and light-headed.

Pay attention to the sensations in your legs during a flight to be safe. (Photo by Jasmin Merdan / Getty Images)

The other thing to look out for, according to Favini, is the rapid onset of shortness of breath. This can be a sign that a clot has formed in, or traveled to, your lungs. “If you’re experiencing these symptoms, especially shortness of breath, let the staff on your airplane know right away,” said Favini.

Related: I got food poisoning before my long-haul flight

How to prevent a blood clot

So, now you know what to look for if you’re developing a blood clot. But, there are certain critical steps you can take to avoid one in the first place.

“Drink lots of fluids, but not with caffeine, which makes you pee more so less fluid in your blood … And avoid alcohol,” said Dr. Oz. “Then, move around every two hours and move feet like stepping on a gas pedal more frequently.”

When TPG spoke to Daniel Giordano, co-founder of Bespoke Treatments Physical Therapy in New York City, about movements and stretches travelers can easily perform on an airplane to promote blood circulation, Giordano said he recommends his clients travel with a device such as a Firefly knee strap. This can gently stimulate the peroneal nerve to promote circulation while performing simple exercises like, as Dr. Oz suggested, pumping your legs.

And for Dr. Narula, the key is anti-embolism socks. These knee-high stockings are specifically designed to put graduated pressure on your legs, which can improve circulation.

Additional reporting by Melanie Lieberman.

Featured photo by katso80 / Getty Images.

Taking a flight or going for a drive that’s longer than three hours? Then let’s talk about blood clots. Why, you ask? For some travelers, blood clots can be a serious risk during long-distance trips, according to the Centers for Disease Control and Prevention. And recently, a fight broke out on a flight when a passenger with a history of blood clots allegedly couldn’t get past another passenger to exit the plane after it landed, TMZ reports.

Roughly one in 1,000 people will develop a blood clot, according to the CDC. And immobility—like the kind you experience on a long trip—is a big risk factor, Thomas Maldonado, M.D., vascular surgeon and professor of surgery at NYU Langone Medical Center, tells SELF.

Here’s what you need to know to protect yourself.

Blood clots typically form in the deep veins of the body.

Blood clots are also known as deep vein thrombosis, as they typically form in the deep veins of the body that aren’t visible through the skin. Most often, they form in the legs, though they can occur in any vein, Dr. Maldonado says. What makes a blood clot dangerous: the potential for it to move through the body’s circulatory system.

“The situation is simple plumbing: You have arteries that bring the blood to the extremities, then you have veins return the blood back to the heart,” Dr. Maldonado says. “When a clot forms in the veins, the clot can dislodge and travel back towards the heart and lodge in the lungs or heart.”

If that happens, it can be dangerous—or even fatal.

Long-distance travel is a risk factor for blood clots because it involves sitting for prolonged periods of time.

While many associate blood clots with just flying, there’s actually an increased risk for blood clots during any type of long-distance travel. “There’s nothing magical or special about flying at 33,000 feet that predisposes you to a blood clot,” Dr. Maldonado says. “When you’re immobile for more than three or four hours at a time, you can develop a clot because blood tends to pool in the legs.” People who are on prolonged bed rest also have an increased risk of blood clots.

When we’re sitting for a long period of time—and not engaging our leg muscles by stretching or walking—the mechanism that keeps blood flowing smoothly doesn’t work per usual. “Our calf muscles propel the blood back , in addition to the natural circulation of the heart pumping,” Dr. Maldonado says. “But when you’re on a long plane trip, you tend to be cooped up and immobile, and that’s a major risk factor.”

He adds that people often become dehydrated on long trips, too, which is another risk factor for blood clots. When the body doesn’t have enough fluids, blood vessels can narrow while blood can thicken, increasing the risk for blood clots.

The signs and symptoms of blood clots are pretty unique—if you have one, you’ll know something’s wrong.

“If you have a tender or painful leg, oftentimes in the calf, and it starts to swell, those are things that could make you suspect that you might have a blood clot,” Dr. Maldonado says. Skin that is warm to the touch and redness of skin are also symptoms of deep vein thrombosis, according to the CDC.

If you’re experiencing one or more of these symptoms during a long-distance trip, Dr. Maldonado says it’s not a “four-alarm fire” and a reason to rush off the plane, but the sooner you get the area checked out—typically by ultrasound—the sooner experts can diagnose a potential clot and intervene with treatment to prevent fatal complications. People with blood clots typically have to take blood thinners for three to six months to prevent their clot from growing and prevent new clots from forming. Sometimes, “clotbusting” medication is also needed to break up a clot.

Everything You Need to Know About Deep Vein Thrombosis (DVT) and Flying

Sitting for extended periods of time in cramped airplane seats may slow blood circulation and increase your risk for DVT. Prolonged inactivity and dry cabin air seem to contribute to the risk.

While there’s some debate as to the connection, some studies have found evidence that the prevalence of DVT within 48 hours of flying on a plane is 2 to 10 percent. That’s the same rate that people in hospitals develop DVT. Staying in a hospital is another risk factor for DVT.

The risk, however, varies greatly among passengers. In general, the longer the flight, the higher the risk. Flights lasting more than eight hours are thought to pose the most risk.

You’re more likely to develop DVT while on a plane if you have any of the other risk factors for it. These include:

  • being over age 50
  • having veins that have been damaged in an injury in the lower extremities, such as from a fractured bone
  • being overweight
  • varicose veins in your legs
  • having a genetic clotting disorder
  • having a family history of DVT
  • having a catheter placed in a vein in the lower extremities
  • taking birth control pills
  • undergoing hormone therapy
  • being pregnant or having given birth in the past month
  • smoking

Flying after blood clots

If you’ve received a diagnosis of DVT in the past or have a family history of blood clots, you’re at an increased risk for developing them while flying. That doesn’t mean you’ll never be able to fly again. Some experts recommend waiting to fly on an airplane for at least four weeks after having DVT or PE, but talk to your doctor about this.

Also talk to your doctor to determine what precautions you should take before flying. In addition to general recommendations for preventing blood clots, they may suggest the following precautions:

  • sitting in an exit row or bulkhead seat to increase legroom
  • wearing compression stockings
  • taking prescription blood thinners or aspirin
  • using a foot or calf pneumatic compression device, which fills with air and squeezes your legs to increase blood flow through the veins
  • exercises for your feet and legs while flying

Air Travel and Deep Vein Thrombosis DVT

Original Article

By Cynthia A. Kos

In a high-paced society, even two-hour flights can seem “long-haul.” This year, researchers flew for as much as 12 hours to attend the XXth Congress of the International Society of Thrombosis Hemostasis (ISTH) held August 6-12, 2005 in Sydney, Australia. It is perhaps fitting that of the multitudes of studies presented, several concerned the association of air travel as a risk factor for deep venous thrombosis (DVT).

Symington and Stack, who reported an apparent increase in DVT in air travelers compared to non-travelers, first described “Economy Class Syndrome” or “Traveler’s Thrombosis” in 1977. The incidence was attributed to cramped seating in the coach cabin. Prolonged periods of inactivity caused by space limitations may slow circulation and produce edema (leg swelling). In addition, bent knees compress the popliteal vein (the deep vein behind the knee), creating a potential site for clot formation over time. Low oxygen, low humidity (dry air), and low cabin pressure at high elevations have a dehydrating effect that concentrate the blood, making it sluggish. This effect is worsened when passengers consume alcohol, or do not adequately replenish fluids lost by dehydration. The body’s natural clot busters typically counter the tendency to clot in these situations; however, in the presence of known hypercoagulable risk factors such as the Factor V Leiden and the Prothrombin G20210 mutations (as well as obesity, smoking, and oral contraceptives) the risk of DVT could be further increased. At this year’s ISTH meeting, several studies attempted to scientifically document a passenger’s general tendency to clot after air travel.

Studies from Ospedale La Carità and University Hospital of Berne (Switzerland) found that changes in clotting enzymes during long periods (6 hours) of sitting increase levels of certain anticoagulants (Tissue Factor Pathway Inhibitor and Antithrombin). This physiologic response resulted in several other adjustments to the clotting cascade that ultimately balanced the effect by increasing Factor V and VIII levels. Thus, the net effect of immobility itself did not necessarily increase a clotting tendency.

Another group led by Anja Schreijer at Academic Medical Center and Leiden University Medical Center (Netherlands) investigated the issue further by comparing thrombin levels in air travelers versus immobile non-flying individuals who watched movies for 8 hours. Thrombin is the product of preliminary reactions in the clotting cascade and activates fibrinogen to form fibrin (the meshwork of a clot). They found a 223% rise in levels due to traveling compared to 46% rise due to immobility. This suggests that a mechanism other than immobility caused the travelers to be at an increased thrombotic risk.

The Dutch research group also headed the WRIGHT Study, which retrospectively surveyed the occurrence of DVT amongst employees of three international companies for four weeks and after a flight of at least four hours. Compared to non-traveling employees, the frequent flyers were found to be 3.65 times more likely to develop a DVT. The risk of developing a clot on a flight was found to be 1 in 5944 flights. If more than one flight was taken in the four-week window, the risk of clotting was slightly elevated. is a non-profit organization dedicated solely to the topic of travel-associated thrombosis, reports that 3-5% of air travelers will develop clots. Despite continued research, case reports, and a physiological basis for increased risk, not all experts agree that air travel is a direct cause of thrombosis due to a lack of large-scale population studies. Such studies are difficult to evaluate, in that the extended period between flight time and presentation of DVT or PE symptoms induces variability.

In the absence of large-scale studies, some airlines feel there is no scientific basis to warrant thrombosis prevention on flights. Ironically, most airline in flight magazines include extensive instructions on how to avoid DVT during flight. However, the apparent increase in risk has prompted some afflicted travelers to site the Warsaw Convention of 1929, which holds airlines liable for damages when passengers are injured by an accident, as grounds to file negligence claims against the carriers. The debate is whether a blood clot is a preventable event, or an individualized reaction to normal flight operations.

The first cases presented in United States district courts began in Texas (Reynolds vs. American Airlines, 2002) and California (Miller and Wylie vs. Continental Airlines, 2003). Since then, hundreds of cases have been filed domestically and internationally. To date, inconclusive medical evidence has resulted in most airlines to disclaim responsibility. Such attention in both the medical and legal arenas emphasizes the importance of the latest medical studies, as they continue to investigate a cause-and-effect relationship between long-haul air travel and thrombosis.

Until it is clarified whether airline travel is or is not a risk factor for thrombosis it appears appropriate for travelers to engage in some DVT prophylaxis exercises, be well hydrated, and avoid alcoholic beverages during flights.

Other Resources

Passport to Safety Brochure

Air Travel – Deep Vein Thrombosis & Pulmonary Embolism

Don’t let cramped conditions put you at risk of DVT. Keep your body moving – even when traveling by airplane. Take proper precautions to reduce the risk of “Economy Class Syndrome.”

Link PDF/Printable Key Points
In Flight Fitness Link Describes simple steps you can take to reduce your chance of developing a blood clot before or after air travel. Includes seated exercises, stretches and general prevention tips.
NPR – National Public Radio Pod Cast Researchers and doctors say obesity, blood abnormalities and being on birth control pills — in combination with other factors — can increase the chance of developing a blood clot during travel.

I Got a Blood Clot on a 6-Hour Flight From Iceland — Here’s How to Keep It From Happening to You

There are a few things people warn you about when you travel: keep your money and your passport close, never leave your luggage unattended and make sure to get up and move around on long-haul flights.

As a travel editor, I’ve heard it all — mostly from the mouths of concerned friends and family members. But nonetheless, I’ve always taken the advice with a grain of salt. After all, I’ve worked in travel media for half a decade, and have written many articles offering that same advice to readers.

Unlike many travelers, I get excited (not stressed), when I enter an airport. I don’t at all mind living out of a suitcase, and long flights — even a previous 18-hour odyssey to Kenya — don’t bother me in the slightest.

Though I’m definitely not a nervous traveler, there is one thing that has always terrified me: the possibility of developing Deep Vein Thrombosis, or DVT.

My colleagues and I have had extensive conversations about the matter, discussing the likelihood of it actually happening to one of us. We always suppressed the concern, noting that DVT mostly affects travelers with preexisting conditions, or passengers who don’t move at all during flights of eight hours or more. Armed with this knowledge, I always try to stretch before a flight, pedal my feet every once in a while and take a walk or two to the lavatory while at altitude. But still, the concern about getting a blood clot on a flight has always loomed in the back of my mind.

And three weeks ago, that fear became a reality.

Let me pause here to share a few things you should know about me: I’m 29 years old, healthy, active — and a serious champ at sleeping on airplanes.

On a recent trip to Iceland, I managed to doze for most of the flight there, and landed rested and ready for adventure. My friends and I spent a week exploring the island nation, including five days backpacking across the country’s Snæfellsnes Peninsula and Landmannalauger trail. We climbed up and over volcanoes, craters and mountains. We bathed in hot springs and marveled at Iceland’s strange, striking landscape. Simply put, it was an amazing trip — but utterly exhausting.

On the overnight flight home from Iceland’s Keflavík International Airport (KEF) to New York City (JFK), I quickly settled into my not-so-spacious WOW Air seat and, once again, fell asleep. This time, unfortunately, it landed me in the emergency room.

As usual I woke up to the “prepare for landing” announcement, some six hours later. I uncrossed my legs and stretched my feet out under the seat in front of me. I immediately noticed that my calves were a bit sore. For a split second, I thought it might be a blood clot, though I quickly dismissed it as a flare-up of paranoia. After all, I reasoned, I had just hiked around Iceland, and it would make sense for my legs to ache.

When we began our descent, I starting to feel a little funny, and thought I might be dehydrated. I gulped some water and got up to use the restroom. My seat was next to the wing, so I had to walk about half the length of the plane to get to the lav. As I did, I began to get very hot and dizzy. I quickly sat down in an empty seat in the front row and asked the flight attendant for an orange juice.

Because we were on WOW Air, of course, the flight attendant first asked me for my credit card. I quickly told her I didn’t have it on me and asked if I could — please and thank you — pay later, because I felt like I was going to pass out. She obliged.

Things started to go fuzzy around me I drank the juice with shaky hands. After about 15 minutes I began to recover, and headed back to my seat for landing. (Come to think of it, I never did pay for that OJ.)

A little freaked out but feeling better, I deplaned and headed for customs. As I walked through the airport I noticed my left leg was now really hurting. I looked at one of my friends and said, “I must have pulled my calf when we were hiking,” and then continued on my way. We headed home, but the pain became increasingly more severe.

Our flight landed on a Monday, and I spent the next two days dismissing my calf pain as a pulled muscle. But the pain intensified. It felt as though I had a charley horse in my leg. By Thursday I was limping and fidgeting in meetings, trying without success to get comfortable. When I got home that evening I told my boyfriend, Jim, about the pain, and how it was getting worse. He leaned down to massage my leg and as he pressed down, I jumped, and immediately started crying.

It. Hurt. So. Bad.

Jim asked if it could be something else, and I let the scary thought of a blood clot resurface. I told him I was probably being neurotic, but maybe, just maybe…

Like any good millennials would do (I hate that we fall into that category, but here we are), we Googled the symptoms for a blood clot. The list was as follows:

Swelling — no.

Redness — no.

Severe calf pain — yes.

Worsening pain — yes.

Recently immobile or on a plane — yes.


It was around 11:00pm, but we decided it was worth going to the ER. After a blood test, a shot of blood thinner and an ultrasound, doctors confirmed I had indeed developed a blood clot in the deep veins of my calf. Otherwise known as (you can probably guess where this is going) deep vein thrombosis.

I stayed in the hospital for monitoring to make certain the clot didn’t move to my lungs or to my heart. After a while I was sent home with a month’s worth of blood thinners, directions to stay active and a long lists of X-rays and tests I had to endure to determine the cause — and to make sure there wasn’t some underlying condition that had triggered the clot.

After a battery of tests and an appointment with a hematologist, it was determined, thankfully, that there was no underlying condition. I had simply fallen asleep so deeply with my legs crossed on the plane that I didn’t move enough, and a clot formed. A freak accident, if you will.

“We look to see if it was provoked or unprovoked. In this case, it was provoked,” my doctor (who prefers to remain anonymous) told me during a follow-up. He cited the nap on the plane as the culprit, and went on to explain that DVT can occur even after just four hours of immobility.

You’re probably thinking what I was: “But wait, don’t we sleep for more than four hours at a time? How come we don’t get blood clots every night?” The answer is that our bodies naturally move around during sleep. When we are confined to a small space, such as a car or a cramped airplane seat, our bodies don’t have that freedom.

So how can you prevent this from happening? My doctor had a few suggestions.

Exercise at your seat

Whether you’re in first class or in economy, roll your ankles regularly and pedal your feet back and forth a dozen or so times each. This will get the blood flowing again, and circulate the blood that can pool in your lower legs back up through your veins.

Get up every hour

They say the length of time during which a blood clot can actually develop is much shorter than most people think — approximately four hours of immobility is when your risk increases. Get up every hour to stretch your legs. Take a walk to the lav. Even the short stroll down the aisle will help keep the blood flowing.

Familiarize yourself with the symptoms

The greatest danger associated with a blood clot in your leg is that it can dislodge and move to your heart or lungs, causing life-threatening conditions. Take a minute to memorize the symptoms of DVT (swelling, redness, pain), and if you think you could have a clot, seek medical attention immediately to prevent additional complications.

Featured image by Demkat/Getty Images

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