A bloody blister in the mouth should be treated as follows: 1. grind and change the sharp tips and edges, extract the residual roots and crowns, remove the bad restorations, modify the movable denture and polish it. 2. eat less food that is too hot and too hard, and avoid seafood with hard shells or spines. 3. a larger bloody blister can be disinfected and then use a sterile syringe to extract the herpes or puncture the wall to remove the bruises. 4. an already broken bloody blister can be treated with The blood blisters that have been broken can be trimmed with sterilized surgical scissors, disinfected by applying iodophor or sprayed with drugs such as pentazocine and tin. 5, pay attention to oral hygiene and cleanliness, with the use of chlorhexidine and other gargles, and take oral antibiotics to prevent infection if necessary.