Mouth ulcers are caused by a variety of factors, often related to minor injuries or irritations inside the mouth. Common causes include:

• Accidental biting of the inside of the cheek, cuts or burns from hot or hard foods and drinks, or irritation from rough teeth, braces, dentures, or fillings

• Emotional stress, hormonal changes (such as during pregnancy or menstruation), and fatigue

• Nutritional deficiencies, particularly of iron, zinc, folic acid, vitamin B, and vitamin D

• Allergic reactions or sensitivities to certain foods (e.g., chocolate, citrus fruits, coffee), toothpaste ingredients like sodium lauryl sulfate, or oral bacteria

• Certain medications, including some NSAIDs, beta blockers, chemotherapy drugs, and radiation therapy

• Underlying health conditions such as hand, foot and mouth disease, oral lichen planus, Crohn’s disease, celiac disease, HIV, lupus, and other autoimmune diseases

Mouth ulcers are not contagious and usually heal on their own, but persistent or recurrent ulcers may require medical evaluation to rule out more serious conditions

. In summary, mouth ulcers result from a combination of physical injury, immune responses, nutritional factors, infections, and underlying systemic conditions.