Cough with phlegm and blood: what to know

Phlegm is mucus produced by the airways. During a common cold or acute bronchitis, inflamed air passages can make mucus and may bleed after repeated coughing. Bronchiectasis can cause recurrent phlegm and blood because widened airways collect mucus. Asthma may cause cough and wheeze, while allergic rhinitis can cause drainage that keeps the throat irritated. Bronchiolitis is more relevant in young children. Acid reflux can maintain a cough without being the source of blood. The blood may also come from the nose or gums and mix with mucus.

Arrange prompt medical advice and describe the colour, amount, frequency, and duration of the blood. Mention fever, wheezing, chest discomfort, breathlessness, recent infection, smoking, and any blood-thinning medicine. Keep hydrated and avoid smoke. If possible, take a clear description or photograph for the clinician, but do not delay emergency care to document it. Do not assume that coloured phlegm alone proves a bacterial infection.

Call emergency services for heavy or continuing bleeding, difficulty breathing, chest pain, fainting, confusion, blue lips, or marked weakness. Seek same-day assessment when blood recurs, fever is significant, you feel increasingly unwell, or you have a known lung disorder. Medical review is also appropriate when a cough continues rather than improving, because the source of bleeding needs examination.

Where is the blood most likely coming from? Could my medicines or a recent infection explain it? What examination or tests might be useful? What should I do if the blood appears again?