Mouth sores, also called recurrent aphthous ulcers, are the most common ulcerative damage in the oral mucosa. The prevalence in the population is about 10 to 30%. It is characterized by periodic recurrent attacks with varying intervals, ranging from short continuous, one after the other, to long intervals of 2 to 3 months. The ulcers tend to occur on the lips, tongue and cheeks, but can also occur on the floor of the mouth, soft palate and pharynx. The etiology of recurrent aphthous ulcers is not fully understood and is complex, and may be related to some predisposing factors. There are many common clinical triggers, such as mental stress, indigestion, constipation, intestinal parasites, sleep deprivation, fatigue, menstrual cycle and menopause. Attention to the influence of hormonal factors, such as the exacerbation of oral ulcers in women before menstruation and the increase in cases in menopausal women, but the lower incidence in women during pregnancy, all indicate that the occurrence of ulcers may be influenced by hormonal changes. The disease has also been found to be associated with genetic factors, immune dysfunction, bacterial infections, certain systemic diseases, micronutrient deficiencies, and local trauma. Many patients with mouth ulcers usually develop them during frequent overtime work, business trips, late nights, and irregular diet due to fatigue, decreased resistance, and irritability.