Mouth ulcers occur due to a variety of reasons, primarily related to minor injuries or irritations inside the mouth. Common causes include accidentally biting the inside of the cheek, irritation from braces, sharp or broken teeth, and burns from hot food or drinks. Injuries from rough dental appliances or toothbrush damage can also cause ulcers. Stress, anxiety, and hormonal changes (such as during pregnancy or menstrual cycles) often contribute to the likelihood of developing mouth ulcers. Nutritional deficiencies, especially of vitamin B12, iron, and folate, can predispose someone to recurrent mouth ulcers. Certain medications, including anti-inflammatories and beta blockers, may cause ulcers as a side effect. Some systemic conditions like inflammatory bowel disease, celiac disease, or autoimmune diseases can manifest as mouth ulcers. Viral infections like herpes simplex can also cause painful sores in and around the mouth. Overall, mouth ulcers are usually harmless and heal on their own, but persistent or multiple ulcers may indicate underlying health issues requiring medical attention.