 These ulcers occur periodically and heal completely between attacks . In the majority of cases , the individual ulcers last about 7 – 10 days , and ulceration episodes occur 3 – 6 times per year . Most appear on the non @-@ keratinizing epithelial surfaces in the mouth ( i.e. anywhere except the attached gingiva , the hard palate and the dorsum of the tongue ) , although the more severe forms , which are less common , may also involve keratinizing epithelial surfaces . Symptoms range from a minor nuisance to interfering with eating and drinking . The severe forms may be debilitating , even causing weight loss due to malnutrition . 
