How common is coughing up blood in lung cancer?

A tumour in or near an airway can irritate its lining and cause blood-streaked mucus or bleeding after coughing. Lung cancer may also be associated with a cough that changes, breathlessness, chest pain, repeated chest infections, hoarseness, tiredness, or unexplained weight loss. These features are not specific to cancer, and coughing up blood can also occur with infection, bronchiectasis, a blood clot, or airway irritation. Assessment is needed to identify the cause.

Arrange prompt medical assessment for any unexplained coughing up blood, even when the amount is small or it happens once. Tell the clinician about smoking or vaping, previous lung disease, recent infection, medicines that affect clotting, and any change in your usual cough. They may examine you and arrange imaging or other tests based on your history. Keep a note of the colour, amount, and timing of the blood.

Seek emergency help if bleeding is heavy or ongoing, or if it occurs with severe breathlessness, chest pain, faintness, confusion, or blue lips. Urgent review is also needed for a new episode with worsening breathing or a rapidly deteriorating cough. Sit upright while waiting for help and take a list of your medicines with you.

What could be causing the blood in my sputum? Which tests would clarify the cause? Could any of my medicines contribute, and what symptoms require emergency care?