Mouth ulcers are sores that appear anywhere inside the mouth and are usually red, yellow, or white. They can be painful and make eating, drinking, and speaking uncomfortable. The most common causes of mouth ulcers are minor tissue injury from dental work, accidentally biting your cheek or tongue, and wearing braces or retainers. Other causes include:

• An allergic reaction to certain bacteria
• Using harsh or abrasive toothpaste
• Eating lots of acidic foods, such as oranges, pineapples, and strawberries
• Hormonal changes during your period
• Stress
• Lack of sleep
• Certain medications
• Skin rashes in the mouth
• Viral, bacterial, and fungal infections
• Chemicals
• Certain medical conditions, such as vitamin deficiencies, Crohn’s disease, celiac disease, reactive arthritis, and lupus

Mouth ulcers can also be caused by injury from a toothbrush, constant rubbing against misaligned or sharp/broken teeth, constant rubbing against dentures or braces, burns from eating hot food, and irritation from strong antiseptics, such as a mouthwash. In many cases, the reason for mouth ulcers is unclear, but triggers are thought to include stress, anxiety, hormonal changes, and certain foods, drugs, or toothpastes.

Its important to note that while most mouth ulcers are harmless and resolve by themselves within 10 to 14 days without the need for treatment, an ulcer that won’t heal may be a sign of mouth cancer. If you get a mouth ulcer that is large, extremely painful, or lasts for a long time without healing, its best to seek the advice of a doctor or dentist.