Blood blisters in the mouth rotting very painful, may be caused by inflammation and infection or oral mucosal ulcers, etc., you can gargle with gargle solution to keep the mouth clean and hygienic, but also under the guidance of a professional doctor for anti-infection, pain relief and so on. 1. Keep the mouth clean: if the mouth blood blisters rotten and painful, you can use the medical advice to clean the mouth with medicinal liquid gargle, such as compound chlorhexidine gargle, etc., to keep the mouth clean. 2. anti-infection treatment: if the inflammation and infection or oral mucous membrane ulcers and other causes of blood blisters rotting in the mouth is very painful, should be under the guidance of the doctor to take anti-inflammatory and bactericidal drugs, such as cefixime, amoxicillin and so on. 3. pain treatment: if the mouth blood blisters rotten, pain is obvious, you can take pain medication under the guidance of a doctor, such as ibuprofen, celecoxib, etc., can relieve oral pain. If the mouth blood blisters rotten pain, it is recommended to go to the stomatology department of the regular hospital as soon as possible, do not delay treatment.