Hi.. Thanks for the query. As per your query Mouth ulcers also known as Canker Sores is a self limiting condition and the exact cause of its occurrence is not known.. Genetics may play some role, others may be vitamin, iron and folate deficiency. Stress can also induce ulcers.. The treatment is mostly based on symptoms. Firstly I would like to tell you that mouth ulcers mostly heal themselves in 8 to 10 days BUT if there is pain and discomfort applying a Topical Anaesthetic agent containing lignocaine or choline salicylate (Mucopain gel or Oragel) can be relieving as it numbs the ulcer and surrounding skin and mucosa so that it is not painful while eating and speaking.. Taking a topical steroid based gel can also be helpful by providing relief from inflammation and discomfort. In case of severe pain Ibuprofen or Calpol can b taken.. Taking multivitamin tablet as prescribed by a doctor if there is any deficiency can be helpful.. At times if there is inflammation and only topical application is not enough oral intake of steroid can be prescribed by a doctor.. Use of antimicrobial mouth rinses can help in keeping infections away.. Other things which can be done are: Avoid citrus fruits as they can initiate sores. Do not take spicy and hot foods.. Keep yourself well hydrated.. Use a soft brush to brush your teeth.. Hope this helps.. Regards..