Black blood blisters in the lining of the mouth are not necessarily cancer, but can also be caused by trauma or mouth ulcers. If you are worried that it may be cancer, you can go to the hospital for a full range of examinations, and you will need to undergo cancer-related treatment after the diagnosis. However, most of the black blood blisters in the mouth are usually caused by trauma, such as self-bite wounds or trauma caused by rough and sharp food, and there is a rupture of blood vessels under the oral mucosa, and the blood that flows out after the rupture is not immediately absorbed and forms blood blisters. If the blood bubble does not affect the diet and function, it can wait for its own slow absorption. If the blood blister is relatively large and affects eating and swallowing, a sterilized sharp instrument can be used to poke it so that the blood flows out slowly and the blood blister is absorbed. After this situation occurs, special attention should be paid in daily life to avoid trauma by not eating particularly hot food or particularly rough food. It is not only bad for the mouth, but also for the throat, which can lead to inflammation of the throat and affect the health.