First-Line Treatment for Canker Sores
For typical canker sores (oral aphthous ulcers), start with topical corticosteroid rinses—specifically betamethasone sodium phosphate 0.5 mg dissolved in 10 mL of water used as a 2-3 minute rinse-and-spit solution four times daily. 1, 2
Initial Topical Corticosteroid Options
The evidence strongly supports topical corticosteroids as first-line therapy for canker sores, with multiple formulation options depending on ulcer location: 3, 4
- For generalized oral ulcers: Betamethasone sodium phosphate 0.5 mg in 10 mL water, rinse and spit for 2-3 minutes, one to four times daily 1, 2
- For localized lesions (buccal mucosa or tongue): Clobetasol 0.05% ointment mixed in 50% Orabase applied twice weekly directly to dried mucosa 1, 2
- Alternative rinse option: Fluticasone propionate nasules diluted in 10 mL water twice daily 1, 2
These recommendations come from the British Journal of Dermatology and American College of Physicians guidelines, representing the highest quality evidence for canker sore management. 1, 2
Pain Management (Concurrent with Corticosteroids)
Pain control should be addressed simultaneously with anti-inflammatory treatment:
- Barrier preparations: Gelclair mucoprotectant gel applied three times daily forms a protective coating that reduces pain and promotes healing 2, 5
- Topical anesthetics: Benzydamine hydrochloride oral rinse every 3 hours, particularly before eating 2, 5
- For severe pain: Viscous lidocaine 2% (15 mL per application) up to 3-4 times daily 2
The evidence shows that while topical anesthetics like benzocaine provide symptomatic relief, they do not address the underlying inflammatory process—hence the priority on corticosteroids. 6, 7
Essential Supportive Measures
These adjunctive measures enhance healing and should be implemented alongside topical corticosteroids:
- Oral hygiene: Warm saline mouthwashes daily to reduce bacterial colonization 2, 5
- Antiseptic rinses: 0.2% chlorhexidine digluconate mouthwash twice daily 2, 5
- Dietary modifications: Avoid crunchy, spicy, acidic foods, hot beverages, and alcohol during healing 2
- Toothpaste selection: Avoid sodium lauryl sulfate-containing toothpastes 4
Critical Pitfall: Rule Out Secondary Candidal Infection
Before or concurrent with corticosteroid therapy, assess for candidal infection, as corticosteroids can worsen fungal overgrowth. 1, 2
If candidal infection is suspected, treat immediately with:
- Nystatin oral suspension 100,000 units four times daily for 1 week, OR 2, 5
- Miconazole oral gel 5-10 mL held in mouth after food four times daily for 1 week 2, 5
When First-Line Treatment Fails
If ulcers persist after 2-3 weeks of appropriate topical corticosteroid therapy:
- Second-line topical: Tacrolimus 0.1% ointment applied twice daily for 4 weeks 1, 2
- Intralesional therapy: Weekly triamcinolone injections (total dose 28 mg) with topical clobetasol 1, 2
- Systemic corticosteroids: High-dose oral prednisone/prednisolone 30-60 mg or 1 mg/kg for 1 week, followed by tapering over the second week for highly symptomatic cases 1, 2
Red Flags Requiring Further Investigation
Obtain blood work and consider biopsy if: 2
- Ulcers persist beyond 3 weeks despite appropriate treatment
- Multiple sites with different morphological characteristics are present
- Systemic symptoms (fever, weight loss, malaise) accompany the ulcers
- Solitary chronic ulcer (to rule out squamous cell carcinoma) 7
The key distinction here is that most simple canker sores heal within 7-14 days with topical corticosteroids, so persistence beyond 3 weeks suggests either inadequate treatment, secondary infection, or an alternative diagnosis requiring investigation. 7, 4