Brief Answer: could be viral, bacterial infection, allergies. Detailed Answer: Hello There, Welcome to XXXXXXX forum, Blisters on the mouth can be because of various reasons like bacterial & viral infections like herpangina, streptococcal infection like oral mucositis, could also be due to nutritional deficiences, allergic reactions, physical or chemical trauma. A thorough clinical examination and evaluation by the Dentist is required. Are the blisters associated with pain? This could also be associated with infected tooth. I would suggest you to approach to an Oral Surgeon for clinical examination and evaluation which helps in exact diagnosis and treatment plan. Meanwhile you apply local anesthetic and antiseptic cream like Hexigel topically over the affected area, do symptomatic treatment at home by maintaining good oral hygiene to prevent superinfection. Take antiseptic mouthwash and lukewarm saline rinses. Take a course of multivitamin suplements. At home take complete balanced diet, drink plenty of water and keep yourself hydrated. Avoid smoking and alcohol consumption as this may worsen the condition. Hope this helps out, Regards, Dr Qazi Ammara.

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