A blood blister inside the mouth does not need to be treated, under normal circumstances, the blood blister can be absorbed and healed by itself in about a week, especially do not use the needle at home to pierce the blood blister, because the needle is not routinely sterilized, the surface with bacteria, it is likely to lead to infection of the blood blister, or even cause a transient bacteremia. Therefore, after the blood blister, it is more important to pay attention to the maintenance of oral health and avoid eating too hard and too hot food, which can cause secondary infection of the blood blister. However, we have to distinguish blood blisters from hemangiomas, which usually do not disappear voluntarily and can last for about a month. If a patient finds a blood blister that does not heal after a month, it is likely that it is not a blood blister, but a hemangioma. If the hemangioma is not healed after a month, it is likely that it is not a blister but a hemangioma.