Pulmonary embolism and leg swelling: what to know

A clot often begins in a deep vein of the leg. Swelling may affect one leg and can occur with aching, tenderness, warmth, or a change in colour. Leg swelling alone has many possible causes, so it cannot confirm a pulmonary embolism. Breathlessness, chest pain that worsens when breathing in, a fast heartbeat, coughing blood, or sudden light-headedness may suggest that a clot has reached the lungs.

If new one-sided swelling occurs with breathing symptoms or chest discomfort, seek emergency medical help. Do not massage the swollen leg or exercise vigorously while waiting for advice. A clinician may assess your symptoms, examine the leg, and arrange tests based on your overall risk. If pulmonary embolism is diagnosed, treatment commonly includes anticoagulation, which reduces the blood's ability to form or extend clots.

Call emergency services immediately for sudden or severe breathlessness, chest pain, fainting, coughing blood, confusion, or blue-grey lips. Urgent assessment is also sensible for unexplained new swelling in one leg, particularly after prolonged immobility, surgery, pregnancy, or a previous clot. Take prescribed medicines as directed and do not stop an anticoagulant without medical advice.

Could the swelling have a cause other than a clot? Which symptoms should prompt emergency help? Do I need imaging or blood tests? If anticoagulation is prescribed, how should I take it and what bleeding symptoms should I report?