Deep vein thrombosis (DVT)

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Deep vein thrombosis (DVT)

Do you need thrombosis prevention necessary on a flight?

Photo of women on an airplane

Deep vein thrombosis (DVT) can develop in your legs on long flights. The risk of that happening is very low for healthy passengers, though. People who have a higher risk of thrombosis can wear compression stockings for prevention.

Deep vein thrombosis (DVT) occurs when a blood clot forms in a vein. It is often caused by blood flowing too slowly through the veins and pooling there. Long flights can increase the risk of thrombosis because you are seated for hours at a time and hardly move your legs during the journey. This can also be a problem on other kinds of long trips, for instance in a car or on a bus.

Deep vein thrombosis is generally very rare during long flights: About 2 out of 10,000 people develop thrombosis with noticeable symptoms on flights lasting longer than four hours. The longer the flight takes, the higher the associated risk. But most of the blood clots that develop during a flight go unnoticed. They are small and dissolve on their own without causing any problems.

Do compression stockings work?

Some travelers wear compression stockings to prevent travel-related thrombosis. The stockings put pressure on the veins, which helps to send blood from the legs back to the heart. Several studies involving a total of more than 2,600 airline passengers looked into whether compression stockings can reduce the risk of thrombosis when flying. Half of the participants wore compression stockings, while the other half didn't.

The stockings used in these studies delivered pressures ranging from 15 to 30 mmHg. That corresponds to compression class 1 or 2 (medical compression stockings are grouped by pressure into four classes, with 4 having the most). The participants were asked to start wearing the stockings at least two hours before the flight. The flights lasted between 7 and 15 hours. Most of the people in the studies had a low or intermediate risk of thrombosis.

None of the participants developed venous thrombosis that caused noticeable symptoms. But closer examinations revealed that a few passengers had blood clots that had not caused any symptoms. The studies showed that the risk of these kinds of blood clots was even lower when compression stockings are worn. The passengers who wore compression stockings also had less swelling in their legs.

Who can benefit from wearing compression stockings?

The risk of developing deep vein thrombosis that causes health problems on longer trips (whether by plane, car or bus) is very low – especially in people who don't have any risk factors for thrombosis. Whether or not you would like to further reduce this risk with compression stockings is a matter of personal choice.

According to doctors, it is generally not necessary to wear compression stockings on long flights. But they could be a good option for people who have particular risk factors and would like to do anything they can to prevent DVT. For instance, the risk is higher in people who have cancer or have had a DVT in the past.

Good to know:

If you aren't sure whether compression stockings would be a good idea, it's best to talk with your doctor before you fly. They can tell whether you have an increased risk of DVT while traveling.

What else can you do?

You can lower the risk of deep vein thrombosis on long flights a little by getting up and walking up and down the aisle occasionally. It is also possible to bend and straighten your ankles and knees from time to time. That activates your calf muscles and helps with the flow of blood. On long car trips, it helps to take regular breaks and stretch your legs. Experts also recommend drinking enough fluids.

Chandra D, Parisini E, Mozaffarian D. Meta-analysis: travel and risk for venous thromboembolism. Ann Intern Med 2009; 151(3): 180-190.

Clarke MJ, Broderick C, Hopewell S et al. Compression stockings for preventing deep vein thrombosis in airline passengers. Cochrane Database Syst Rev 2021; (4): CD004002.

Deutsche Gesellschaft für Angiologie - Gesellschaft für Gefäßmedizin (DGA). S2k-Leitlinie Diagnostik und Therapie der Venenthrombose und der Lungenembolie. AWMF register no.: 065-002. 2023.

Deutsche Gesellschaft für Chirurgie (DGCH), Deutsche Gesellschaft für Innere Medizin (DGIM). S3-Leitlinie Prophylaxe der venösen Thromboembolie (VTE). AWMF register no.: 003-001. 2026.

IQWiG health information is written with the aim of helping people understand the advantages and disadvantages of the main treatment options and health care services.

Because IQWiG is a German institute, some of the information provided here is specific to the German health care system. The suitability of any of the described options in an individual case can be determined by talking to a doctor. informedhealth.org can provide support for talks with doctors and other medical professionals, but cannot replace them. We do not offer individual consultations.

Our information is based on the results of good-quality studies. It is written by a team of health care professionals, scientists and editors, and reviewed by external experts. You can find a detailed description of how our health information is produced and updated in our methods.

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Do you need thrombosis prevention necessary on a flight?

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Created on July 14, 2026

Next planned update: 2029

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Institute for Quality and Efficiency in Health Care (IQWiG, Germany)

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