GP warns never to ignore coughing up blood as scans can reveal tumours or blood clots

A London GP has urged anyone who coughs up blood to see their doctor immediately, saying the symptom can signal a range of conditions from benign causes to life-threatening disease.

Dr. Clare Thompson, who works at the Cadogan Clinic in London, told the Daily Mail that patients often underestimate the amount of blood they see, and clinicians treat every case seriously. "I often find patients say, 'Well, I've just had a spattering of blood', and actually it's quite a lot, and the opposite is true, too," she said. "When it comes to coughing up blood, it could be something benign, or it could be something deathly serious—but there isn't a sliding scale for us, we take every case seriously."

Dr. Thompson told the newspaper that even small amounts — from a speck in mucus to a teaspoon-sized blot — should prompt urgent medical review because the symptom can be a sign of a serious underlying problem, including a life-threatening blood clot in the lungs known as a pulmonary embolism.

In most cases, a general practitioner will arrange imaging to investigate the lungs, she said. That assessment commonly includes chest X-rays or more detailed scans, and patients are typically offered a follow-up appointment about six weeks later to ensure the cause has resolved. Imaging can reveal tumours or areas of shadowing in the lungs that are consistent with chronic lung disease such as chronic obstructive pulmonary disease (COPD).

Medical experts describe coughing up blood, medically called haemoptysis, as a symptom with a wide range of causes. Infectious illnesses such as pneumonia and bronchitis, chronic inflammatory conditions, structural airway disease and malignancy can all present with blood in sputum. Pulmonary embolism is a particularly acute and dangerous cause that requires immediate investigation.

Dr. Thompson emphasized that early assessment helps clinicians distinguish between causes that can be managed in primary care and those that require urgent hospital treatment. Diagnostic imaging, together with clinical examination and history-taking, guides decisions about further tests, specialist referral and urgent interventions where needed.

Public health guidance and clinicians say patients should seek prompt assessment if they notice blood when coughing, especially if the bleeding is recurrent, associated with breathlessness, chest pain, fever, weight loss, night sweats or a history of smoking. Those on blood-thinning medications should also report haemoptysis promptly because anticoagulants can increase bleeding risk.

Careful evaluation aims to identify treatable infections, manage chronic lung conditions, detect malignancy at an earlier stage and rule out life-threatening events such as pulmonary embolism. Follow-up after the initial assessment helps ensure that transient causes have resolved and that any required further investigation or treatment is started without delay.

Dr. Thompson's comments underscore a common clinical message: while some causes of coughing up blood are minor, the symptom should not be dismissed. Early presentation to a GP or emergency services, timely imaging and appropriate follow-up remain central to safe care when haemoptysis occurs.