Which topical corticosteroid and application regimen should be used for symptomatic relief of a typical aphthous ulcer (canker sore)?

Topical Corticosteroid Treatment for Canker Sores (Aphthous Ulcers)

For typical aphthous ulcers (canker sores), use clobetasol propionate 0.05% ointment mixed 1:1 with Orabase applied directly to dried mucosa twice daily for localized lesions, or betamethasone sodium phosphate 0.5 mg dissolved in 10 mL water as a rinse-and-spit solution 2-4 times daily for multiple or widespread ulcers. 1, 2, 3

First-Line Topical Corticosteroid Options

For Localized Single Ulcers

• Apply clobetasol propionate 0.05% ointment mixed 1:1 with an oral adhesive paste (Orabase) directly to the dried ulcer surface twice daily. 1, 2, 4
• The mucosa must be dried with gauze before application to ensure adherence. 4
• This combination provides superior early pain relief compared to ointment alone. 4

For Multiple or Widespread Ulcers

• Use betamethasone sodium phosphate 0.5 mg dissolved in 10 mL of water as a 2-3 minute rinse-and-spit solution 2-4 times daily. 1, 2, 3
• Alternative: Dexamethasone 0.1 mg/mL mouth rinse used the same way. 3, 5
• Continue treatment for 5-7 days or until marked improvement occurs. 5

Alternative First-Line Option

• Fluticasone propionate nasules diluted in 10 mL water twice daily can be used as an alternative rinse. 1

Pain Management Adjuncts

• Apply viscous lidocaine 2% approximately 15 mL per dose 3-4 times daily before meals for severe pain. 2, 3
• Use benzydamine hydrochloride oral rinse or spray every 3 hours, particularly before eating. 2, 3
• Barrier preparations such as Gelclair or Gengigel mouth rinse/gel applied three times daily provide mucosal protection and additional pain control. 1, 3

Supportive Oral Care

• Perform warm saline mouth rinses daily to maintain hygiene. 2, 3
• Use antiseptic oral rinses twice daily: either 0.2% chlorhexidine digluconate (diluted 50% if irritating) or 1.5% hydrogen peroxide. 2, 3
• Apply white soft paraffin ointment to lips every 2 hours if lip involvement is present. 2, 3

Second-Line Treatment for Non-Responsive Ulcers

If ulcers do not improve after 1-2 weeks of topical corticosteroid therapy:

• Consider intralesional triamcinolone injections weekly (total dose approximately 28 mg) in conjunction with continued topical clobetasol. 1, 2, 3
• Alternatively, apply tacrolimus 0.1% ointment twice daily for 4 weeks for refractory lesions. 1, 3

Systemic Therapy for Severe or Highly Symptomatic Cases

• For highly symptomatic or recurrent ulcers, use oral prednisone or prednisolone 30-60 mg (or 1 mg/kg) daily for 1 week, then taper over the second week. 1, 2, 3
• This approach is reserved for cases where topical therapy has failed or when ulcers are causing significant functional impairment. 6

Treatment Duration and Monitoring

• Topical corticosteroids should be applied for at least 5-7 days or until marked lesion improvement is observed. 2, 5
• Re-evaluate within 1-2 weeks; lack of improvement warrants escalation to second-line therapy or specialist referral. 3
• Any ulcer persisting beyond 2 weeks despite appropriate treatment requires biopsy to exclude malignancy. 2, 3, 7

Critical Pitfalls to Avoid

• Do not taper corticosteroids prematurely before achieving disease control. 2, 3
• Do not prescribe corticosteroids without ensuring adequate antimicrobial coverage if secondary infection (candidiasis) is suspected—treat concurrent candidal infection with nystatin oral suspension 100,000 units four times daily or miconazole oral gel. 1, 2
• Do not delay specialist referral for non-healing ulcers beyond 2 weeks, as this may indicate underlying malignancy or systemic disease. 2, 3, 7
• Avoid sodium lauryl sulfate-containing toothpastes, hard/acidic/salty foods, alcohol, and carbonated drinks during active ulceration. 6

Evidence Quality Note

The recommendation for clobetasol 0.05% mixed with Orabase is supported by high-quality clinical trial data showing superior efficacy for both pain relief and healing compared to ointment alone. 4 Dexamethasone ointment has been validated in a large multicenter randomized controlled trial (240 patients) demonstrating significant improvement in ulcer size reduction, pain relief, and healing ratio (83.33% vs 54.70% placebo) with no detectable systemic absorption. 5