Suddenly grow a big blood blister in the mouth must do a good job of oral care or recommended for symptomatic treatment (i.e., the use of syringes to draw out the fluid in the blisters). 1. After the appearance of blood blisters in the mouth, we should keep the mouth clean and avoid too hot or too hard food to reduce the stimulation of the blood blisters; at the same time, we can follow the doctor’s instructions to use gargles (such as cotrimoxazole gargle or rehabilitation of the new liquid) to anti-inflammatory and reduce the swelling and to promote the healing of the blood blisters. 2. When blood blisters appear in the mouth and affect oral functions such as eating, it is recommended to consult a doctor to extract the blood and tissue fluid inside the blood blisters to promote their effective healing; the above gargles can also be used as prescribed by the doctor. In addition, the presence of large blood blisters in the mouth should be excluded from the factors of blood system diseases (such as leukemia, purpura, etc.), in order to avoid the delay of the disease and the occurrence of serious accidents.