Deep Vein Thrombosis

Key facts

• DVT is a blood clot that forms inside a deep vein, most often in the calf or thigh.
• Warning signs include swelling, warmth, and a dull ache or tightness in one limb that worsens on standing or walking; some clots cause no symptoms at all.
• Treated with anticoagulants: warfarin or newer direct oral anticoagulants such as rivaroxaban, usually for three to six months.
• Seek emergency care for chest pain, rapid breathing, or coughing up blood, which can mean the clot has reached the lungs.

What causes it

A DVT forms when a blood clot develops inside a deep vein, most often in the calf or thigh. Prolonged immobility is a major trigger: long periods of sitting, bed rest, or reduced movement after surgery slow blood flow enough to let a clot form. Other risk factors include recent surgery, pregnancy, certain hormonal medicines, smoking, and inherited clotting disorders.

Recognising a clot in the leg

The affected limb may swell, feel warm, and develop a dull ache or tightness that gets worse when standing or walking. Skin over the area can look red or take on a bluish tinge. Some DVTs cause no obvious symptoms at all, which is why sudden leg swelling after a period of immobility should always be assessed promptly. Chest pain, rapid breathing, or coughing up blood point to a pulmonary embolism, a medical emergency that needs immediate care.

How DVT is managed

Treatment centres on anticoagulants, medicines that stop a clot from growing and lower the risk of new ones forming. Warfarin has long been the standard oral option, though it needs regular blood tests to keep the dose in the right range. Newer direct oral anticoagulants such as rivaroxaban work at a fixed dose without routine monitoring and are now widely used as first-line treatment. Both approaches fall under heart and blood pressure management more broadly. Treatment usually runs three to six months, sometimes longer depending on the underlying cause and how severe the clot was.

When to see a doctor

See a doctor promptly for new leg swelling, warmth, or pain, especially after a long flight, surgery, or a period of bed rest. Treat chest pain, breathlessness, or coughing up blood as a medical emergency and seek immediate care.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.