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Deep vein thrombosis (DVT) is more common if you can't or don't move about for long periods. This may be why some research has found that people are more at risk of DVT if they go on a long-distance journey, such as a long flight.

If you've had DVT before, or if you are at risk of getting it, you should discuss with your doctor ways to prevent it before you book your travel. (For more about the risk of DVT, see What is deep vein thrombosis?)

You might need to take drugs to reduce your risk of blood clots. Or you might need to wear special elastic stockings called compression stockings. They help the blood keep flowing up through your legs and back to your heart, instead of staying in your lower legs and causing clots. Your pharmacist can measure you to help you buy the right size of stockings.

Whether or not you are at high risk, you can do exercises and other things that might help prevent DVT. We can't say for sure if these things work as there haven't been any studies of them.

Here are some of the things experts recommend.^{1 2}

• Don't take sleeping pills.
• Don't drink a lot of alcohol.
• Try to exercise your legs while seated. Bend and straighten your legs, feet and toes while sitting down, every half hour. Make a circle pattern with each foot in turn.
• Press the balls of your feet down hard against the floor or a footrest to increase the blood flow in your legs.
• Avoid sitting still for long periods. Take short walks around the cabin of your airplane or train compartment. If you are in a car or bus, be sure to take a short walk whenever you stop for a break.

Even if you are not at high risk, you might think about wearing compression stockings. Some, but not all, research has shown that these stockings reduce the risk of getting DVT on long-distance flights.³ But the stockings are not suitable for everyone, so ask your doctor about them first.

You should get medical help quickly if you get any of the symptoms of DVT. The main symptom is a swollen, painful leg. To learn more, see What are the symptoms of deep vein thrombosis? If you get DVT because of sitting still on a long-distance journey, you might not notice any pain or swelling right after the trip. It can take hours or even a day or so for you to get any symptoms.

This information is for educational use only, and is not a substitute for prompt professional medical advice. Readers should always consult a physician or other professional for advice and treatment. ©BMJ Publishing Group Limited 2008. All rights reserved.