Health condition
Deep vein thrombosis (DVT)
A DVT is a blood clot in a deep vein, usually the leg. Prompt diagnosis and anticoagulation prevent the clot travelling to the lungs and limit long-term leg damage.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
The symptoms to recognise, when to seek help, which specialist to see, and what treatment usually involves.
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Typical symptoms: one calf or leg becoming swollen, tight, warm and tender over hours to days - though some DVTs cause little to notice
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Call 999 for sudden breathlessness, chest pain or coughing blood - these suggest a pulmonary embolism
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Specialist: a consultant in vascular medicine or haematology usually leads assessment and treatment
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Treatment is anticoagulation, usually with a DOAC tablet for at least three months; duration depends on whether the clot was provoked and your ongoing risk
Understanding the condition
What it is and what happens next.
What causes it, how it is diagnosed, and the treatment routes available in the UK.
What it is and how it feels
DVTs form when blood flow slows, the vein wall is injured or the blood is more clottable - after surgery, immobility, long journeys, pregnancy, hormonal treatment, cancer or with inherited clotting tendencies. Diagnosis combines a risk score, a D-dimer blood test and an ultrasound scan of the leg veins.
Diagnosis and treatment routes
Modern anticoagulants (DOACs) work immediately, need no routine monitoring and have made treatment far simpler. The key specialist questions afterwards are how long to anticoagulate, whether testing for an underlying cause is worthwhile, and how to reduce the risk of post-thrombotic syndrome in the affected leg. In many parts of the UK, routine NHS referrals for this kind of problem currently take 20-45+ weeks, whereas an initial appointment with a private consultant is typically available within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a consultant in vascular medicine or haematology. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any of the emergency symptoms described above.
Frequently asked
Common questions about Deep vein thrombosis (DVT).
Quick, plain-English answers to what people ask us most.
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What is a DVT?
A DVT (deep vein thrombosis) is a blood clot in a deep vein, usually in the leg. Prompt diagnosis and anticoagulation treatment prevent the clot travelling to the lungs, where it could cause a dangerous pulmonary embolism.
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What causes a DVT?
Common risk factors include prolonged immobility (such as long-haul flights or after surgery), certain medical conditions, pregnancy, hormonal medications, and inherited or acquired clotting tendencies.
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What are the symptoms of a DVT?
Typical symptoms include swelling, pain, warmth, and redness in one leg, though some clots cause minimal or no noticeable symptoms, which is why clinical suspicion and testing matter when risk factors are present.
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Is a DVT dangerous?
Yes, the main danger is that part of the clot can break off and travel to the lungs, causing a potentially life-threatening pulmonary embolism, which is why prompt diagnosis and treatment are so important.
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How is a DVT treated?
Treatment involves anticoagulant (blood-thinning) medication to prevent the clot growing and reduce pulmonary embolism risk, usually continued for at least three months, alongside supportive measures like compression stockings.
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How is a DVT diagnosed?
Diagnosis typically involves an ultrasound scan of the leg veins, sometimes alongside a blood test (D-dimer) to help assess the likelihood of a clot before deciding on imaging.
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How long does DVT treatment last?
Anticoagulant treatment typically continues for at least three months, with the exact duration depending on whether there was a clear, temporary trigger or ongoing risk factors that might warrant longer-term treatment.
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Can a DVT be prevented?
Yes - staying mobile during long journeys or after surgery, wearing compression stockings when recommended, and, for higher-risk individuals, preventive anticoagulant medication can all help reduce DVT risk.
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DVT vs a pulmonary embolism - what's the difference?
A DVT is a clot within a leg vein, while a pulmonary embolism happens when part of that clot breaks off and travels to block a blood vessel in the lungs - the latter is the more immediately dangerous complication of the former.
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When should I seek help for suspected DVT?
Seek prompt medical assessment for new leg swelling, pain, or redness, and call 999 immediately if you develop sudden breathlessness or chest pain, which could indicate a pulmonary embolism.