Although mouth ulcers are very common, there are many reasons why they occur. Mouth ulcers are small sores that appear on the inside of the mouth, under the tongue, on the inside of the lips, or on the gums.

The main reasons for this are as follows:

Main causes of mouth ulcers
Minor injuries: Accidental biting of the inside of the mouth, injury while brushing, or burning while eating hot food can cause mouth ulcers.

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Digestive problems: Digestive problems such as stomach upset, constipation, and acidity are the main causes of mouth ulcers.

Nutritional deficiency: Deficiency of vitamin B12, folic acid, iron, and zinc in the body plays a major role in the development of mouth ulcers.

Stress: Many people experience mouth ulcers when they are under heavy workload or stress.

Hormonal changes: This can occur during menstruation and other hormonal changes in women.

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Side effects of some medications: Some medications, such as pain killers, can cause a sore mouth.

Mouthwash/paste: Sodium lauryl sulfate (SLS), a substance found in some mouthwashes or toothpastes, can cause allergies in some people.

Dental defects: Stains on the teeth or the sharp edges of the molars can cause cuts on the inside of the mouth.