There are many reasons why mouth ulcers grow all the time, commonly due to low immunity or other diseases of the body in the oral cavity. Mouth ulcers are a common disease of the oral mucosa, with localized redness, swelling and pain, which can seriously affect life and eating. The cause of oral ulcers is not clear and there are multiple causative factors. The most common cause of mouth ulcers is low body immunity, and some mouth ulcers have certain genetic factors. Parents who have a high incidence of mouth ulcers have a higher chance of having children with mouth ulcers. Mouth ulcers may also be related to vitamin deficiency or iron deficiency, resulting in increased brittleness of the oral mucosa, which can easily bite through the mucosa and cause mouth ulcers. Oral ulcers may also be traumatic, and the crown and root remnants, bad restorations and sharp tooth tips may also cause mucosal ulcers, so it is necessary to remove the bad restorations, grind the sharp tooth tips or remove the root remnants in time to remove the irritating factors to avoid long-term stimulation that may cause cancer. Eating shelled seafood, such as shrimp and crab, can easily cause oral ulcers due to minor trauma to the oral mucosa in the morning. Mouth ulcers may also be related to emotions. Excessive stress in life or emotional tension can trigger mouth ulcers. It must be treated actively to reduce the frequency of attacks and accelerate their healing. As mentioned above, there are many causes of mouth ulcers. If it does not heal for more than two weeks, pathological examination should be performed to rule out the possibility of cancer.