When to contact a doctor
Even a small unexplained blood streak needs prompt medical assessment. More than a few streaks, continuing bleeding, breathing difficulty, chest pain, a racing heartbeat or faintness needs emergency care: call 108. Do not delay because an earlier episode stopped or because there is no pain.
What you may notice
Blood may appear as streaks in mucus or as fresh blood coughed from the chest. Blood from the nose or mouth, and blood that is vomited, can look similar but follow different pathways. Note the amount, recurrence and associated fever, chest pain or breathlessness.
Lungs and branching airways
What could cause it?
Possible causes include chest infection, tuberculosis, widened damaged airways called bronchiectasis, a lung tumour, or a clot in the lung circulation. Medicines affecting clotting may worsen bleeding. A respiratory assessment, chest imaging and sometimes bronchoscopy help locate the source; the appearance of the blood alone is not diagnostic.
How interventional radiology may help
Treating the cause, such as infection, is essential. In significant or recurrent bleeding from bronchial or other systemic arteries supplying the lung, IR can identify and embolise the responsible vessels. Bronchoscopy, surgery or another treatment may be appropriate. Embolisation controls a bleeding source; it does not by itself cure tuberculosis, bronchiectasis or a tumour.
Further reading: detailed assessment and treatment options
Patient information sources
References are in English.
Educational information, not a diagnosis. The causes listed are examples, not a complete list. Tests and treatment depend on your individual assessment.