Blood clots

Blood clots can be very serious and need to be treated quickly. Staying healthy and active can help prevent them.

What a blood clot in a leg can look like

A blood clot in a leg is called deep vein thrombosis (DVT).

Call 999 or go to A&E if:

  • you're struggling to breathe
  • someone has passed out

This could be a blood clot in the lungs (pulmonary embolism), which needs to be treated immediately.

Check if you're at risk of blood clots

Blood clots are rare in young, healthy people.

You're more likely to get them if you:

  • are staying in or recently left hospital – especially if you can't move around much (like after an operation)
  • are overweight
  • smoke
  • are using combined hormonal contraception such as the combined pill, contraceptive patch or vaginal ring
  • have had a blood clot before

There are also other things that increase your risk of clots.

How to prevent blood clots

If you're at a high risk of blood clots – for example, you're in hospital – follow the advice of your care team about preventing clots.

This may involve wearing stockings that improve your blood flow or taking medicine to reduce the risk of clots (anticoagulants).

There are also things you can do to help avoid clots.


  • stay active – even just taking regular walks can help
  • drink plenty of water to avoid dehydration – you're more likely to get a clot if you're dehydrated
  • try to lose weight if you're overweight
  • wear flight stockings or flight socks to improve your blood flow on long flights – a pharmacist can advise you about this


  • do not sit for long periods without moving, if you can avoid it
  • do not drink lots of alcohol – this can make you dehydrated
  • do not smoke
[Last reviewed 2018-01-26]