Recurrent Mouth Ulcers (Canker Sores): Causes, Prevention, and Treatment

What Are Recurrent Aphthous Stomatitis (RAS)?

Recurrent, painful, round/oval ulcers with yellow-white floor and erythematous halo on non-keratinized oral mucosa. Affects 20% of population.

Common Triggers and Causes

• Nutritional deficiencies: Iron, zinc, folate, vitamin B12, vitamin D.
• Hormonal fluctuations: Menstrual cycle, pregnancy.
• Psychological stress: Alters immune function, increases susceptibility.
• Immune-mediated conditions: Celiac disease, IBD (Crohn's, UC), Behçet's disease, HIV/AIDS.
• Genetics: Family history in ~30–40%.
• Medications: NSAIDs, beta-blockers, chemo, alendronate, nicorandil.
• Food sensitivities: Acidic (citrus, tomatoes), spicy, chocolate, coffee, gluten, sodium lauryl sulfate (SLS) in toothpaste.
• Trauma: Cheek biting, dental work, sharp teeth/braces.
• GERD: Acid reflux irritates oral mucosa.

Prevention Strategies

• Balanced diet; supplement if deficient (test first).
• SLS-free toothpaste (e.g., Sensodyne Pronamel, Biotène).
• Stress management (CBT, mindfulness).
• Avoid trigger foods; keep food diary.
• Soft-bristle brush; gentle technique.
• Treat underlying conditions (celiac, IBD, GERD).

Treatment

• Topical corticosteroids: Triamcinolone 0.1% paste, fluocinonide gel, clobetasol ointment.
• Barrier agents: Orabase, Zilactin.
• Antimicrobial rinses: Chlorhexidine 0.12% (short-term).
• Severe/refractory: Systemic steroids, dapsone, colchicine, thalidomide, biologics (specialist care).

When to See a Professional

• Ulcers >2 weeks, unusually large (>1 cm), frequent (>3–4×/year)
• Fever, weight loss, genital/skin lesions, eye symptoms (suggest Behçet's)
• No response to OTC measures