What is the treatment for a painful sore at the corner of the mouth?

Treatment of Painful Sore at Corner of Mouth

Apply white soft paraffin ointment to the affected area immediately and then every 2 hours, combined with topical antifungal therapy if angular cheilitis (fungal infection) is suspected. 1, 2

Initial Assessment and Diagnosis

The location at the "outside corner of the mouth" strongly suggests angular cheilitis, which is commonly caused by Candida infection, often combined with bacterial colonization. 1 However, if the lesion appears vesicular or crusted, consider herpes labialis (cold sore) as an alternative diagnosis. 1

First-Line Topical Management

For Angular Cheilitis (Most Likely)

• Apply white soft paraffin ointment every 2 hours to protect and moisturize the affected area 1, 2
• Treat presumed Candida infection with nystatin oral suspension 100,000 units four times daily for 1 week, or miconazole oral gel 5-10 mL held in the mouth after food four times daily for 1 week 1, 3
• Use antiseptic oral rinse such as 0.2% chlorhexidine digluconate mouthwash twice daily to reduce bacterial colonization 1, 3, 2
• Consider combination antifungal-corticosteroid therapy to address both infection and inflammation 2

For Herpes Labialis (If Vesicular/Crusted Lesions Present)

• Initiate oral antiviral therapy immediately at first symptoms - this is more effective than topical treatment 1
• Valacyclovir 2 grams twice daily for 1 day (two doses 12 hours apart) is the preferred regimen, reducing episode duration by approximately 1 day 4, 5
• Alternative: Famciclovir or acyclovir in appropriate doses 1
• Apply white soft paraffin ointment to lips every 2 hours for symptomatic relief 1

Pain Management

• Benzydamine hydrochloride oral rinse or spray every 3 hours, particularly before eating 1, 3
• If inadequate pain control, use viscous lidocaine 2%, 15 mL per application, 3-4 times daily 1, 3
• Avoid alcohol-containing products which can cause additional irritation 1, 2

Oral Hygiene Measures

• Clean the mouth daily with warm saline mouthwashes to reduce bacterial load 1, 3, 2
• Use a soft toothbrush or oral sponge to gently clean the area 1
• Apply mucoprotectant mouthwash three times daily (e.g., Gelclair) to protect ulcerated surfaces 1, 3

When to Escalate Treatment

If No Improvement After 1-2 Weeks:

• Obtain bacterial and fungal cultures from the lesion 1, 2
• Consider topical corticosteroid therapy: betamethasone sodium phosphate 0.5 mg in 10 mL water as rinse-and-spit four times daily 1, 3
• For localized lesions: clobetasol propionate 0.05% mixed with Orabase applied directly to dried mucosa 1, 3

For Refractory Cases:

• Tacrolimus 0.1% ointment twice daily for 4 weeks 3
• Consider systemic corticosteroids (prednisone 30-60 mg daily for 1 week with taper) for severe cases 3

Critical Pitfalls to Avoid

• Do not use chronic white soft paraffin on lips as it promotes mucosal dehydration and increases infection risk 1
• Do not delay antiviral therapy for herpes labialis - treatment must begin at first symptoms (tingling, itching) before visible lesions develop for maximum effectiveness 4, 5
• Do not assume all corner-of-mouth lesions are herpes - angular cheilitis requires antifungal therapy, not antivirals 1, 2
• Obtain cultures if secondary infection suspected or if lesions fail to heal, as HSV reactivation or bacterial superinfection may complicate treatment 1

Prevention Strategies

• Avoid frequent washing with hot water and skin irritants 2
• Use alcohol-free moisturizing creams twice daily to maintain lip hydration 2
• Apply sunscreen SPF 15 to lips and reapply every 2 hours when outdoors 2