Deep vein thrombosis (DVT)


Deep vein thrombosis (DVT) is a blood clot in the vein, usually the leg. DVT can be dangerous. Get medical help as soon as possible if you think you have DVT.

Ask for an urgent GP appointment or call 111 if:

You think you have DVT.

Symptoms of DVT in the leg are:

  • throbbing or cramping pain in 1 leg (rarely both legs), usually in the calf or thigh
  • swelling in 1 leg (rarely both legs)
  • warm skin around the painful area
  • red or darkened skin around the painful area
  • swollen veins that are hard or sore when you touch them

These symptoms also happen in your arm or tummy if that's where the blood clot is.

Call 999 or go to A&E if:

You have symptoms of DVT, such as pain and swelling and:

  • breathlessness
  • chest pain

DVT can be very serious because blood clots in your veins can break loose, travel through your bloodstream and get stuck in your lungs, This is called a pulmonary embolism.

A pulmonary embolism can be life threatening and needs treatment straight away.

Who is more likely to get DVT

A DVT is more likely to happen if you:

  • are over 60
  • are overweight
  • smoke
  • have had DVT before
  • take the contraceptive pill or HRT
  • have cancer or heart failure
  • have varicose veins

There are also some temporary situations when you're at more risk of DVT. These include if you:

  • are staying in or recently left hospital - especially if you cannot move around much (like after an operation)
  • are confined to bed
  • go on a long journey (more than 3 hours) by plane, car or train
  • are pregnant or if you've had a baby in the previous 6 weeks
  • are dehydrated

Sometimes DVT can happen for no obvious reason.

How DVT is diagnosed

If a doctor thinks you have DVT, you should be referred to hospital within 24 hours for an ultrasound scan. The scan shows whether blood is flowing normally through the vein.

You may also have an X-ray of the vein (venogram). For this, you will be injected with a dye to show where the blood clot is.

Treatment of DVT

You may have an injection of an anticoagulant (blood thinning) medicine called heparin while you're waiting for an ultrasound scan to tell if you have a DVT.

After DVT is diagnosed, the main treatment is tablets of an anticoagulant medicine, such as warfarin and rivaroxaban. You will probably take the tablets for at least 3 months.

If anticoagulant medicines are not suitable, you may have a filter put into a large vein - the vena cava - in your tummy. The filter traps and stops a blood clot travelling to your heart and lungs.

A newer treatment involves breaking up and sucking out the clot through a small tube in the vein. You usually need to take anticoagulant medicine for several months after this treatment.

DVT in pregnancy is treated differently. It is treated with anticoagulant injections for the rest of the pregnancy and until the baby is 6 weeks old.

Recovery from DVT

Some lifestyle measures will help you recover from DVT.

After you leave hospital, you will be encouraged to:

  • walk regularly
  • keep your affected leg raised when you're sitting
  • delay any flights or long journeys until at least 2 weeks after you start anticoagulant medicine

Tips to prevent DVT


  • stay a healthy weight
  • stay active - taking regular walks can help
  • drink plenty of fluids to avoid dehydration - DVT is more likely if you're dehydrated


  • do not sit still for long periods of time - get up and move around every hour or so
  • do not cross your legs while you're sitting, it can restrict blood flow
  • do not smoke - get support to stop smoking
  • do not drink lots of alcohol

Going on a long journey

If you're travelling for 3 hours or more by plane, train or car, there are things you can do during the journey to reduce your risk of DVT. These include wearing loose clothing, drinking plenty of water, avoiding alcohol and walking around when possible.

Going into hospital

If you go into hospital, your healthcare team should check your risks of DVT.

If they think you're more likely to get DVT, you may be given treatment to prevent it, such as medicine or compression stockings (knee-high elastic socks that help your blood circulation), while you're in hospital.

You may continue treatment after you leave hospital because a blood clot can happen weeks later.

You can also help protect yourself against DVT while you're in hospital by:

  • staying active and walking around if you can
  • moving your toes (up and down) and ankles (in circles) if you have to stay in bed - your healthcare team may give you some exercises to do

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 24/05/2022 11:56:23