Why does pneumonia cause coughing up blood?

Inflamed breathing passages are more fragile, and forceful coughing can disturb small surface blood vessels. This may show as streaks or small amounts of blood in phlegm. Coughing Up Blood is a common presentation of Pneumonia, but blood from the mouth, nose, stomach, or other lung conditions can look similar. It should not be assumed to be pneumonia without a clinical assessment.

Contact a clinician promptly whenever you cough up blood, even if the amount seems small. If possible, note whether it is bright red or mixed with mucus, whether it has happened again, and any fever, chest pain, weight loss, recent illness, or use of medicines that affect bleeding. Do not ignore a change simply because a cough has been present for some time. A clinician may examine you and arrange testing based on your symptoms.

Seek emergency help now if you cough up more than a small streak of blood, the bleeding continues, or it occurs with severe breathlessness, chest pain, dizziness, fainting, confusion, or blue or grey lips. Emergency assessment is also needed if you feel rapidly worse. Do not drive yourself if you are weak, dizzy, or struggling to breathe.

Ask what may be the source of the blood, whether your chest needs imaging or other tests, whether any current medicine could contribute, and what amount or associated symptom should trigger emergency care.