Mouth Ulcer (Canker Sore) Pain: Symptoms and Causes

Mouth ulcers (aphthous ulcers) are shallow, round/oval lesions with a yellow-white pseudomembrane and erythematous halo. They cause significant discomfort disproportionate to size.

Typical Sensations

• Stinging/Burning: Especially with acidic, salty, spicy, hot, or rough foods.
• Pain on Function: Eating, drinking, speaking, swallowing, brushing teeth.
• Tingling/Prodrome: 6–24h before ulcer appears.
• Localized Tenderness: Touch elicits sharp pain.
• Swelling/Heat Sensation: Inflammatory response.

Severe/Atypical Features (Suggesting Other Etiology)

• Fever, malaise, lymphadenopathy → viral (HSV, coxsackie), Behçet's, PFAPA.
• Large (>1 cm), deep, scarring → major aphthae.
• Multiple, frequent, persistent >2 weeks → systemic workup (celiac, IBD, HIV, nutritional deficiency, malignancy).
• Genital/ocular ulcers → Behçet's, Reiter's, herpes.

Common Triggers

• Trauma (biting, dental work, abrasive food)
• Stress, sleep deprivation
• Hormonal fluctuations (menstrual cycle)
• Nutritional deficiencies (iron, B12, folate, zinc)
• Sodium lauryl sulfate (SLS) in toothpaste
• Food sensitivities (chocolate, coffee, nuts, citrus, tomatoes, gluten)
• Medications (NSAIDs, beta-blockers, bisphosphonates, chemo)
• Genetic predisposition

Symptomatic Management

• Topical anesthetics (benzocaine, lidocaine)
• Protective barriers (Orabase, hydroxypropyl cellulose)
• Topical corticosteroids (triamcinolone 0.1% dental paste, fluocinonide gel)
• Antimicrobial rinses (chlorhexidine 0.12%)
• SLS-free toothpaste
• Avoid triggers

Most minor aphthae heal in 7–10 days. Recurrent or severe cases warrant investigation for systemic causes.