There are several reasons for blood in saliva: 1. gingivitis, periodontitis, that is, inflammation of the gums caused by poor oral hygiene, prone to gum bleeding, especially in the morning, especially prone to bleeding. 2. blood in saliva may be caused by gingival tumors, gingival tumors may cause bleeding gums. 3. blood in saliva may be due to tooth extraction trauma, tooth extraction trauma in about 3-4 days will have the phenomenon of bleeding. 4.