Coughing up blood after flu

Influenza can leave the airways inflamed, and repeated forceful coughing may break tiny surface vessels, producing a small streak in mucus. Blood can also accompany a secondary chest infection such as pneumonia. Bronchiectasis may cause recurrent bleeding in people with underlying airway damage. A pulmonary embolism, tuberculosis or lung cancer are other causes a clinician may consider when the pattern does not fit simple post-viral irritation; the fact that flu came first does not prove the explanation.

Pay attention to whether the cough is improving or worsening, whether fever returned, and whether breathing is harder than during the original illness. These details help determine how quickly you need review.

Rest, take fluids in small regular amounts and avoid smoke or strenuous activity while recovering. Note the colour and amount of blood and whether it is mixed through mucus or appears as fresh drops. Contact a clinician promptly if it returns, continues or appears alongside fever, chest discomfort or increasing cough. Continue prescribed treatment as directed, but do not start antibiotics or stop blood-thinning medicine without medical advice.

Call emergency services for heavy bleeding, clots, breathlessness, sharp chest pain, faintness, confusion, blue lips or a rapid deterioration. Arrange same-day medical advice for recurrent blood, a fever that returns after improvement, worsening weakness or a cough that is becoming more severe. Emergency assessment is needed even if the bleeding stops when these warning signs occur.

Ask whether you may have a post-flu chest infection, whether a chest examination or imaging is appropriate, and which changes should prompt emergency care. Tell the clinician when flu symptoms began, whether fever returned, how the blood looked, and your full medicine history.