Travel and blood clots

When you sit still for long periods of time – such as when you’re travelling – you increase your risk of blood clots. This is because sitting still slows the blood flow from your legs back to your heart.


  • Restricted leg room can slow the flow of blood even more, particularly when the back of the seat in front is pressing on your shins.
  • When blood forms clots in the deep veins of the legs, usually the calves, it’s called deep vein thrombosis.
  • If that clot passes up the veins and to the heart it can become stuck in one the blood vessels supplying the lungs. This can cut off the oxygen supply to the body. This is known as a pulmonary embolism. It can be fatal.

People at risk

Some people have a higher risk of deep vein thrombosis, including:

  • pregnant women
  • women taking the pill
  • people who have had a recent operation
  • those over 40
  • smokers
  • people with cardiovascular disease
  • people with a family history of blood-clotting disorders.

If you fit into any of these categories, you should be extra careful to prevent deep vein thrombosis when you are travelling.

Other things you should know

  • Passengers flying in first class or business class can also get blood clots in their legs, even though there is more leg room.
  • Blood clots can form on journeys as short as 3 hours.
  • Deep vein thrombosis can happen on long bus or train journeys as well as on planes.


If you think you might have a deep vein thrombosis, see your doctor. The symptoms are usually:

  • swelling on one lower leg
  • tenderness deep in your calf
  • the veins under the skin of your lower leg becoming more prominent (darker and raised) and sometimes the skin being dusky compared to the other leg.

Sometimes deep vein thrombosis can affect both legs, and can spread above your knee.

Call Healthline 0800 611 116 if you are unsure what you should do.


You can reduce your chance of deep vein thrombosis by following these tips, especially if you’re in a high risk group.

  • Try to get a seat with extra leg room, such as one next to an emergency exit.
  • Drink plenty of water in order to reduce dehydration (which increases the risk of blood clots), especially if you’re drinking alcohol or drinks containing caffeine.
  • Don't stay in your seat throughout the flight – walk around the plane often. An aisle seat makes this much easier.
  • While seated, exercise your calf muscles every half-hour by flexing and rotating your ankles for a few minutes.
  • Sleep only for short periods and don’t take sleeping pills that could keep you motionless in your seat for hours.
  • Consider wearing support stockings during the flight to reduce the risk of clots.
  • Avoid wearing tight clothing around your waist.

If you think you have an increased risk of thrombosis and are worried about it, contact your doctor.

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