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Flying and prevention of DVT and PE

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Travellers' thrombosis is the occurrence of venous thromboembolism (VTE) (deep vein thrombosis (DVT) or pulmonary embolism (PE)) related to travel.

  • unfortunately, good quality randomised controlled trials are lacking in this area (1,2)
    • according to a research, all forms of transport involving a journey of 4 hours or more are associated with DVT
    • the risk of flight related DVT is increased in both shorter and taller individuals and in the overweight and is associated with location in a window seat
    • risk is also increased in combined oral contraceptive pill use and carriage of factor V Leiden
    • there is no evidence to suggest that dehydration is an important factor
  • the UK Department of Health (DH) recommends that patients with a personal or family history of VTE or clotting abnormalities, a history or current treatment of cancer, those who have suffered a stroke or have had recent major surgery, obtain medical advice before travelling.
    • the DH has also issued further specific advice to travellers (3)
      • Before the trip
        • some experts advise patients who have had a hip or knee replacement to avoid long haul flights for three months
        • patients who are in a high-risk group (including women taking the pill or HRT) may wish to consider the use of elastic stockings
      • During the trip

Blood clots - Deep venous thrombosis (DVT) and venous thromboembolism (VTE)

Risk criteria

Risk reduction advice for passengers

Low Risk

-no history of DVT / VTE

-no recent surgery (four weeks)

-no other known risk factor

Keep mobile.Drink plenty of non alcoholic drinks.Do not smoke. Avoid caffeine and sedative drugs.

Medium Risk

-history of DVT/VTE

-surgery lasting more than 30 minutes between 4 and 8 weeks ago

-known clotting tendency

-pregnancy -obsesity (BMI.30)

As for 'low risk'with addition of compression stockings

High Risk

-previous DVT with known additional risk including known cancer

-surgery lasting more than 30 minutes within the last 4 weeks

As for moderate risk but sub cutaneous injections of Enoxoparin 40 mg before the flight and on the following day

  • After the trip
    • if you develop swollen, painful legs, especially if one is more affected than the other, or if breathing difficulties occur, see a local doctor urgently or visit the nearest accident and emergency department.

There is also guidance suggesting that individuals with a high risk of developing VTE, who wish to fly, should wear graduated elasticated compression stockings.

  • in the general population, there is evidence that prophylactic use of graduated compression stockings during air travel reduces the rate of flight related DVT (5,6)

Also a review of air travel and venous thromboembolism stated (7):

  • for the majority of healthy air travellers the risk of deep vein thrombosis or pulmonary embolus is very small
  • risk of symptomatic venous thromboembolism increases with flight duration
  • most air travellers who develop thrombosis have additional risk factors for venous thromboembolism
  • patients at risk of venous thromboembolism should be warned of the dangers of long haul flights
  • compression stockings reduce the incidence of deep vein thrombosis
  • low molecular weight heparin is effective, but should only be used in those at highest risk
  • there is currently no evidence that aspirin is effective


  • the use of AES for prevention of VTE during and after long-haul travel is not routinely recommended. When used, care should be taken to ensure an appropriate fit


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