Overview

Mouth ulcers (aphthous ulcers / canker sores) are small painful sores on the soft tissues inside the mouth. Very common, affecting up to 20% of the population. Most heal within 1-2 weeks without treatment. Recurrent aphthous stomatitis (RAS) requires investigation. Any ulcer lasting more than 3 weeks must be evaluated by a dentist to exclude oral cancer.

Symptoms

• Round or oval sore with white or yellow centre and red border
• Burning or tingling sensation 1-2 days before the ulcer appears
• Pain worsening with eating, drinking, or speaking
• Usually 3-10mm in diameter; major ulcers exceed 10mm
• Recurring ulcers at similar or different sites

Causes & Risk Factors

• Minor trauma: biting the cheek, sharp food, ill-fitting dentures
• Stress and anxiety — the most common trigger for recurrent ulcers
• Nutritional deficiencies: iron, vitamin B12, folate
• Hormonal changes: menstrual cycle, pregnancy
• Certain foods: citrus, tomatoes, spicy foods
• Systemic conditions: coeliac disease, Crohn's disease, Behcet's disease, HIV

Complications

• Difficulty eating and drinking affecting nutrition, especially in children
• Major ulcers may take 6 weeks to heal and may scar
• Any ulcer lasting more than 3 weeks may indicate oral cancer — always investigate

Diagnosis

Most aphthous ulcers are diagnosed clinically by appearance. Blood tests screen for nutritional deficiencies and systemic disease in frequent recurrence. Biopsy is indicated for persistent (over 3 weeks), non-healing, indurated, or atypical ulcers.

Treatment

• Most minor ulcers heal spontaneously in 7-14 days without treatment
• Topical anaesthetics (benzocaine, lidocaine gel) for pain relief
• Topical corticosteroids (triamcinolone paste): reduce inflammation and speed healing
• Chlorhexidine mouthwash reduces secondary infection and pain
• Vitamin supplementation if deficiency confirmed

Prevention

• Avoid known food and stress triggers
• Switch to SLS-free toothpaste if ulcers are frequent
• Maintain balanced nutrition; check B12 and iron levels
• Any ulcer lasting more than 3 weeks must be reviewed by a dentist immediately

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