What is the first‑line treatment for recurrent aphthous ulcers (canker sores) in a typical adult?

Treatment for Canker Sores (Oral Aphthous Ulcers)

Start with topical corticosteroids as first-line therapy for canker sores, specifically betamethasone sodium phosphate 0.5 mg dissolved in 10 mL water as a rinse-and-spit solution 2-4 times daily, or clobetasol 0.05% gel/ointment applied directly to accessible lesions 2-4 times daily. 1, 2, 3

Initial Management Strategy

Protective Barriers and Symptom Relief (Start Immediately)

• Apply white soft paraffin ointment to each ulcer every 2 hours to create a protective barrier 1, 2
• Perform warm saline mouth rinses 3-4 times daily to reduce bacterial colonization 1, 2
• Use benzydamine hydrochloride 0.15% rinse or spray every 2-4 hours, especially before meals, for anti-inflammatory and analgesic effects 1, 2

Pain Control

• Apply viscous lidocaine 2% directly to ulcers before eating for rapid symptomatic relief 1, 2
• Consider barrier preparations like Gelclair applied three times daily for mucosal protection 1, 3
• Avoid alcohol-containing mouthwashes as they exacerbate pain and delay healing 2

First-Line Pharmacologic Therapy (Topical Corticosteroids)

If pain persists after 48 hours of protective measures, escalate to topical corticosteroids:

For Multiple or Widespread Ulcers:

• Betamethasone sodium phosphate 0.5 mg in 10 mL water as rinse-and-spit 2-4 times daily 1, 3
• Dexamethasone 0.1 mg/mL mouth rinse, swish and spit 4 times daily 1, 2
• Fluticasone propionate nasules diluted in 10 mL water twice daily 3

For Localized, Accessible Ulcers:

• Clobetasol propionate 0.05% gel or ointment applied directly 2-4 times daily 1, 2, 3
• Triamcinolone acetonide 0.1% paste applied to dried ulcer 2-4 times daily 1, 4

The evidence supporting topical corticosteroids comes primarily from expert opinion and observational data rather than high-quality randomized trials, but the European League Against Rheumatism provides Level IB evidence supporting their use 2. These preparations are often available over-the-counter or through pharmacist consultation in many countries 2.

Second-Line Therapy for Refractory Cases

If No Improvement After 1-2 Weeks:

• Intralesional triamcinolone injections weekly (total dose 28 mg) for persistent ulcers 1, 3
• Tacrolimus 0.1% ointment applied twice daily for 4 weeks as an alternative 1, 3

For Highly Symptomatic or Severe Cases:

• Systemic corticosteroids: Prednisone/prednisolone 30-60 mg or 1 mg/kg for 1 week, then taper over the second week 1, 3, 5
• Do not taper corticosteroids prematurely before disease control is established 1

Prophylaxis for Recurrent Aphthous Stomatitis (≥4 Episodes/Year)

For patients with frequent recurrences, colchicine is the first-line systemic prophylactic therapy, particularly effective when associated with erythema nodosum or genital ulcers. 1, 3, 6

Escalation Options for Resistant Cases:

• Azathioprine 2.5 mg/kg/day for severe cases with frequent recurrences 3
• Thalidomide (most effective but limited by teratogenicity and peripheral neuropathy risks) 3, 6
• TNF-alpha inhibitors or apremilast in selected cases 1

Critical Pitfalls to Avoid

• Do not use petroleum-based products alone chronically, as they may dehydrate mucosa and increase secondary infection risk 2
• Avoid alcohol-containing mouthwashes that exacerbate pain and delay healing 2
• Do not apply topical anesthetics immediately before eating, as this impairs swallowing reflexes and raises aspiration risk 2
• Do not taper corticosteroids prematurely before disease control is established 1
• Treat concurrent candidal infection with nystatin oral suspension or miconazole oral gel before or during corticosteroid therapy 3

When to Refer or Escalate

• Refer to specialist if ulcers persist >2 weeks or fail to respond to 1-2 weeks of appropriate treatment 1
• Consider biopsy for ulcers lasting over 2 weeks to exclude malignancy or systemic disease 1, 7
• Obtain complete history and physical examination to rule out systemic diseases (Behçet's, inflammatory bowel disease, HIV, hematologic disorders) 7, 8

Adjunctive Measures

• Avoid hard, acidic, salty foods and toothpastes containing sodium lauryl sulfate 5
• Avoid carbonated drinks 5
• For dry mouth, recommend sugarless chewing gum or salivary substitutes 1
• Use antiseptic oral rinses (0.2% chlorhexidine digluconate or 1.5% hydrogen peroxide) twice daily 1

The treatment hierarchy prioritizes topical therapy first due to minimal side effects, reserving systemic medications for severe or refractory cases 5, 8. The primary goals are pain relief, reduction of ulcer duration, and restoration of normal oral function, with secondary goals of reducing recurrence frequency 6, 5.