What is the diagnosis and treatment for a patient who bit their lip and later consumed spicy food, now presenting with a swollen sore and grey covering on the underside of the lip one week later?

Traumatic Oral Ulcer with Secondary Infection (Likely Morsicatio Labiorum with Bacterial/Fungal Superinfection)

This is a traumatic oral ulcer from the initial lip bite, complicated by the spicy food irritation, now presenting with a grey covering that suggests either fibrinous exudate or secondary infection requiring immediate topical antimicrobial therapy combined with supportive oral care. 1, 2

Clinical Diagnosis

The grey covering on a swollen lip ulcer one week post-trauma is most consistent with:

• Morsicatio labiorum (self-induced lip injury) presenting as a macerated grey-white patch, which is a recognized clinical entity often misdiagnosed 1
• The grey covering likely represents either fibrinous exudate from the healing wound or secondary bacterial/fungal colonization 2, 3
• The spicy food exposure acted as an additional irritant, delaying healing and potentially introducing microbial contamination 4

Immediate Treatment Protocol

First-Line Antimicrobial and Anti-inflammatory Therapy

Start combination topical therapy immediately:

• Apply white soft paraffin ointment to the lips every 2 hours to protect the ulcerated surface and maintain moisture 4, 5
• Use antiseptic oral rinse with 0.2% chlorhexidine digluconate mouthwash (10 mL twice daily) to reduce bacterial colonization; dilute by 50% if it causes excessive soreness 4, 5
• Apply benzydamine hydrochloride oral rinse or spray every 3 hours, particularly before eating, for anti-inflammatory effect and pain control 4, 5

Oral Hygiene Protocol

• Clean the mouth daily with warm saline mouthwashes using gentle sweeping motions to remove debris without causing additional trauma 4, 6
• Use a soft oral sponge or soft toothbrush to maintain hygiene without disrupting the healing tissue 6
• Avoid alcohol-containing mouthwashes as they cause additional pain and impair healing 4, 6

Consider Secondary Infection Treatment

If the grey covering persists beyond 48 hours or worsens, add:

• Nystatin oral suspension 100,000 units four times daily for 1 week OR miconazole oral gel 5-10 mL held in mouth after food four times daily for 1 week to cover potential Candida superinfection 4, 7
• Take oral and lip swabs for bacterial and fungal culture if secondary infection is suspected 4
• If bacterial infection is confirmed, prescribe appropriate antibiotics based on culture results 4

Topical Corticosteroid for Persistent Inflammation

If significant inflammation persists after 3-4 days:

• Apply betamethasone sodium phosphate 0.5 mg in 10 mL water as a 3-minute rinse-and-spit preparation four times daily 4
• Alternatively, apply clobetasol propionate 0.05% mixed in equal amounts with Orabase directly to the ulcer daily for more severe cases 4

Dietary and Behavioral Modifications

• Eliminate all irritating foods: avoid tomatoes, citrus fruits, hot drinks, spicy foods, hot foods, raw foods, and crusty foods until healing is complete 4, 6
• Consume only soft, moist, low-acidity foods if tolerated 4
• Stop any habitual lip biting, chewing, or sucking to prevent recurrence 1
• Avoid smoking and alcohol as both impair mucosal healing 6

Pain Management

For inadequate pain control with benzydamine:

• Use viscous lidocaine 2%, 15 mL per application as a topical anesthetic before eating 4, 5
• For severe discomfort, cocaine mouthwashes 2-5% three times daily may be considered under medical supervision 4

Follow-Up and Red Flags

• Evaluate treatment response within 2 weeks 5, 6
• If no improvement after 2 weeks, reevaluate for correct diagnosis, as chronic non-healing ulcers may represent malignancy or systemic disease 3, 8
• Watch for signs of complications: pain disproportionate to injury (suggesting deeper tissue involvement), spreading erythema, fever, or lymphadenopathy 4, 2
• Persistent grey covering despite treatment warrants biopsy to rule out neoplastic processes, as oral cancers can mimic benign traumatic ulcers 3

Common Pitfalls to Avoid

• Do not use petroleum-based products chronically on lips as they promote mucosal dehydration and create an occlusive environment that increases secondary infection risk 6
• Do not close or suture traumatic oral wounds as this increases infection risk; allow healing by secondary intention 4
• Do not dismiss persistent ulcers as "just trauma" - any oral ulcer lasting beyond 2-3 weeks requires biopsy to exclude malignancy 3, 8
• Do not use first-generation cephalosporins, macrolides, or clindamycin alone if systemic antibiotics are needed, as these have poor activity against oral polymicrobial flora 4