Whether benign, as a nosebleed, or a more serious cause, coughing up blood
should be taken seriously and the cause
determined. This will require examination, first, by a lung specialist who will do a bronchoscopic exam including autofluorescence and perhaps order other tests, such as a CT scan of the lungs. If there is no source of blood in the lungs or large airways, you should then have an ENT specialist exam.