Mouth ulcers due to excessive stomach heat are primarily caused by improper diet. For this condition, one should consume more foods and fruits that reduce stomach heat, such as apples, pears, watermelon, and grapefruit, as well as vegetables like lettuce and celery to effectively regulate stomach heat and improve symptoms. It is crucial to drink plenty of water, urinate frequently, and avoid consuming foods that increase internal heat and irritant foods to prevent exacerbating the condition. One must also ensure adequate rest, avoid excessive fatigue, particularly staying up late, and spend time in the sun to increase calcium absorption.