What should you know about coughing up fresh blood?

Fresh blood may appear bright red, streaked through mucus, or mixed with phlegm. A forceful or prolonged cough can irritate small blood vessels in the throat or airways. Chest infections such as pneumonia can also cause blood-stained mucus; bronchiectasis may cause repeated episodes because widened airways collect mucus and bleed more easily.

Less common but serious causes include a pulmonary embolism, tuberculosis, or lung cancer. These conditions can present with coughing up blood, but the symptom alone cannot identify the cause. Blood from the nose, mouth, or stomach can sometimes be mistaken for blood coughed up from the lungs.

Arrange prompt medical advice even if the amount seems small, particularly when the episode is new or recurring. Note the colour and approximate amount, whether it was mixed with mucus, how often it happened, and any medicines that affect clotting. Do not drive yourself if you feel faint or short of breath. Keep any prescribed medicines available for the clinician, but do not stop a blood thinner unless a healthcare professional tells you to.

A clinician may examine your nose, throat, and chest and ask about infection symptoms, smoking, recent travel, injury, and previous lung problems. Further tests may be chosen according to those findings.

Call emergency services now if the bleeding is more than a few streaks, is continuing, or comes with difficulty breathing, chest or upper-back pain, a fast heartbeat, faintness, confusion, blue or grey lips, or marked weakness. These signs can indicate significant bleeding or a serious problem affecting the lungs.

Seek same-day medical care for a first episode, repeated blood-stained phlegm, fever, worsening cough, night sweats, unexplained weight loss, or new breathlessness. Children, older adults, pregnant people, and anyone taking anticoagulants should seek advice promptly because their assessment may need to be prioritised.

You could ask: Where might the blood be coming from? Do my symptoms suggest an infection, clot, or another lung condition? Which warning signs mean I should return urgently? Should I change any medicine that affects clotting? What follow-up or tests will help explain a recurring episode?