A black blood blister on the tongue instantly may be caused by eating too hard or too hot food or biting the tongue, it is best to let the blood blister recover on its own, if it breaks it may cause infection. When the blood blister on the tongue does not fall off, it is best not to eat spicy, rough food, or too hard, too hot food, to avoid damage to the blood blister. If the blood blister is large or does not disappear for a long time, it is recommended to go to the hospital in time, and the doctor will puncture the blood blister under aseptic operation, so that the blood in the blood blister can be released to reduce the local tension, which is conducive to the disappearance of the blood blister. In order to avoid the appearance of blood blisters on the tongue, do not eat too hard, too hot food in normal times, if there is a sense of bite interference with the tongue blood blisters, it is best to go to the hospital in a timely manner, the appropriate treatment.