Why does pulmonary embolism cause coughing up blood?

A pulmonary embolism is a blockage in a blood vessel of the lung, often caused by a clot. If an area of lung is damaged because its blood supply is affected, small amounts of blood can mix with mucus and be coughed out. Coughing Up Blood is a common presentation of Pulmonary Embolism. It can also be caused by airway infection, irritation, or other lung conditions, so the source needs medical evaluation.

Coughing up blood should be assessed urgently, especially when it is new or unexplained. Seek emergency care immediately if it occurs with chest pain, shortness of breath, fainting, a racing heartbeat, or feeling very unwell. If possible, note whether the blood is streaking in mucus or comes in a larger amount, but do not delay seeking help to monitor it. Avoid taking medicine for a suspected clot unless it has been prescribed for you.

Call emergency services now for more than a small streak of blood, ongoing bleeding, severe breathing trouble, severe chest pain, collapse, confusion, or blue or grey lips. Tell the emergency team if you take anticoagulants or have recently had surgery, reduced mobility, or a previous blood clot. These details can guide urgent assessment.

Ask what may have caused the bleeding, which tests are needed, and whether any medicines increase bleeding risk. If treatment for pulmonary embolism is started, clarify how to take it and which bleeding symptoms require immediate help.