Mouth ulcers may be very annoying to the patient at times. Common causes of mouth ulcers include VItamin B complex deficiencies, stress, diabetes mellitus, sharp impinging structures in the mouth, worm infestations in children, variety of bacterial and viral infections etc. Treatment depends on identification of the underlying cause and managing the same. For example in Vitamin B complex deficiencies, supplementation of the Vitamin will ease the patient's symptoms. Good DIabetic control, effective stress management, correction of any sharp teeth etc will cause relief to the patient.