<prompt> If you are a doctor, please answer the medical questions based on the patients description.Hello Doctor! this is swetha from chennai..this query for my brother who is 20 years old and affected by mouth ulcer for the past 4 years..he undergone for many treatments but no use..due to this bad mouth ulcer his studies gets spoiled..kindly help him out to get rid of this problem.. i would be grateful if you answer this quetion  <response>: Hello:Thank you for choosing Chat Doctor. You did not mention if he is under medication for general health.Check with the physician reg. This if any. Some Chat Doctor. A clear cause for ulcers has not been given yet, however poor oral hygiene, stress, deficiencies can attribute. He can use a lidocaine based gel like GEMSTONE before foodthis makes the area little numb, for temporary relief. Gargle thrice daily with warm saline water. Use a soft tooth brush. Have a tobacco free, non-alcoholic, stress-free lifestyle. Check if any sharp tooth causes this ulcer, if so it should be rounded. Regards. 