Hello and Welcome to ‘Ask A Doctor’ service. I have reviewed your query and here is my advice. Understanding your concern. As per your query you have blood blisters in the mouth which seems to be due to canker sores, hot and acidic food, any injury to mucosa, stress, hormonal changes or some medicines and could be due to systemic conditions such as Stevens Jones Syndrome. They usually go away within few days by their own. I would suggest you to :-- Start doing warm saline and baking soda rinses. - Apply orabase gel before having meal to reduce burning sensation. - Also start taking Vitamin B complex supplement. - Do betadine rinses also for twice a day. If condition doesn t subside in a weak then consult oral pathologist for proper diagnosis and then go for biopsy by taking sample from oral mucosa. Doctor may prescribe steroid ointment or drug like sucralfate . Hope I have answered your query. Let me know if I can assist you further.