Deep Vein Thrombosis

A deep vein thrombosis (DVT) is a blood clot in one of the deep veins; usually in the legs. It can occur when people are inactive for long periods or there is a reason for the blood to clot more easily. Complications include a pulmonary embolus, where a blood clot breaks off and goes to the lungs, and can be fatal. The risk of a DVT after a long plane flight is extremely low, but the risk may be significant and increases for longer flights or trips where there is prolonged inactivity compounded by dehydration. It is not limited to people in economy class. Seek assessment and treatment as soon as possible if you have swelling, pain or discomfort in your leg or legs as you may have a deep vein thrombosis.


DVT usually presents with lower leg pain and swelling after periods of inactivity.
Pulmonary Embolus presents with rapid onset cough, shortness of breath and chest pain.


The advice given depends on your level of risk.
Prevention for most travellers will include walking, regular activity and being well hydrated. Drink lots of water on long flights.
For travellers with increased risk on flights greater than five hours, additional measures should include well fitted below knee compression stockings.
For travellers at high risk of DVT and in addition to the above measures, injections of low molecular weight heparin (blood thinner) may be recommended. New oral blood thinning medication may be a better alternative. Aspirin is not recommended for prevention of venous thrombosis.


  • Who's at highest risk?

    Previous DVT is the highest risk factor of all but other people at high risk include patients on chemotherapy, those who have had recent surgery or with a known personal or family history of blood clots or a blood clotting disorder. Anything restricting blood flow (e.g. plaster casts) increases the risk of DVT, as does obesity, smoking, being on the oral contraceptive pill, hormone treatment or being an older traveller.

  • What should I do if I think I have a DVT?

    Seek medical attention as soon as possible if you think you might have a DVT, you have just had a long flight and/or have any of the above risk factors.