A black blood blister on the inside of the mouth requires no special treatment if it is caused by a tooth bite. If it is caused by pemphigus, it needs to be treated with general measures and medication. 1. tooth bite: if recently in the process of eating and chewing food, the teeth bite into the oral mucosa of the situation, resulting in the rupture of the capillaries under the mucosa bleeding, after a period of time will become black blood bubbles, under normal circumstances, if there is no other discomfort, do not need to carry out special treatment, can be gradually absorbed on their own. 2. Pemphigus: Some types of pemphigus occurring in the oral cavity will appear in the inner wall of the mouth to grow a black blood bubble situation. Patients need to adjust the diet structure, pay attention to maintain water, electrolytes and acid-base balance, use saline to wipe the mucous membrane every day. Patients should use glucocorticosteroids such as prednisolone and dexamethasone as prescribed by the doctor, and immunosuppressants such as cyclophosphamide and cyclosporine should be used if the treatment is not effective. It is recommended that patients with a black blood blister on the inside of the mouth go to the hospital to clarify the specific cause and then treat it.