NHS website

Pulmonary embolism

Find out what a pulmonary embolism is and what causes it, plus how it's diagnosed, treated and prevented.

10 December 2018


A pulmonary embolism is a blocked blood vessel in your lungs. It can be life-threatening if not treated quickly.

See a GP if:

  • you feel pain in your chest or upper back
  • you have difficulty breathing
  • you're coughing up blood

You may also have pain, redness and swelling in one of your legs (usually the calf). These are symptoms of a blood clot, also called deep vein thrombosis (DVT) ↗.

Call 999 or go to A&E if:

  • you have severe difficulty breathing
  • your heart is beating very fast
  • someone has passed out

These could be signs of a pulmonary embolism or another serious condition.

Treating a pulmonary embolism

If your GP thinks you've got a pulmonary embolism, you'll be sent to hospital for further tests and treatment.

At hospital, you'll probably be given an injection of anticoagulant medicine ↗ before you get any test results.

Anticoagulants stop blood clots getting bigger and prevent new clots forming.

If tests confirm you have a pulmonary embolism, you'll continue with anticoagulant injections for at least 5 days.

You'll also need to take anticoagulant tablets for at least 3 months.

You can expect to make a full recovery from a pulmonary embolism if it's spotted and treated early.

Reduce your pulmonary embolism risk

You can reduce your risk of a pulmonary embolism by taking measures to prevent DVT.

A pulmonary embolism commonly occurs when part of the blood clot dislodges itself from your leg and travels up to your lungs, causing a blockage.

If you're being treated in hospital for another condition, your medical team should take steps to prevent DVT.

You can occasionally develop DVT on journeys lasting more than 6 hours.

You can take steps to reduce your risk of travel-related DVT.


  • sit comfortably in your seat and lie back as much as possible
  • wear loose-fitting clothing
  • make sure you have plenty of leg room
  • drink water regularly
  • take regular breaks from sitting
  • bend and straighten legs, feet and toes every 30 minutes while seated
  • press the balls of your feet down hard against the floor every so often
  • wear flight socks


  • do not sit for long periods without moving
  • do not drink alcohol
  • do not drink too much coffee and other caffeine-based drinks
  • do not take sleeping pills