Coughing up blood with influenza: what to know

Influenza can cause a dry, forceful cough that irritates the lining of the throat and bronchial tubes. This may leave a small red streak in mucus. Influenza can also occur alongside or be followed by pneumonia, which may cause worsening fever, chest discomfort, breathlessness, and a productive cough. A clot in the lung, bronchiectasis, tuberculosis, and other illnesses are less obvious possibilities that a clinician may need to exclude.

Arrange medical advice and describe the bleeding rather than assuming it is part of influenza. Rest, drink fluids if suitable, and avoid smoking or vaping. Keep track of temperature, breathing, chest symptoms, and whether the blood returns or becomes more visible. Bring a list of medicines and medical conditions. Do not use someone else’s antibiotics or add medicines that affect clotting without professional advice.

Go to emergency care for difficulty breathing, chest pain, faintness, confusion, blue-grey lips, a racing heartbeat with weakness, or bleeding that is heavy, persistent, or repeated. Seek same-day assessment when fever is worsening, you are unable to drink, or your cough and breathing deteriorate after an initial improvement. These changes can signal a complication rather than uncomplicated influenza.

Ask whether your symptoms suggest pneumonia or another cause, whether an examination or chest imaging is needed, and which treatments are appropriate for your health history. Ask how to recognise deterioration and where to seek help overnight.