A character is either dying or badly injured when they start bleeding from the mouth.
And it's the signs of death and causes Hemotypsis
is the coughing up of blood or blood-stained mucus from the bronchi, larynx, trachea, or lungs. In other words, it is the airway bleeding. This can occur with lung cancer, infections such as tuberculosis, bronchitis, or pneumonia, and certain cardiovascular conditions
Alternatively, the bleeding may simply come an injury to the mouth itself (cut lip, bit tongue, etc.).
The following tags are aliased to this tag: mouthbleed (learn more).
This tag implicates blood (learn more).