What causes a swollen lip and how is it treated?

Swollen Lip: Causes and Treatment

Immediate Assessment Priority

A swollen lip requires rapid differentiation between allergic/anaphylactic reactions requiring emergency treatment and infectious/inflammatory causes requiring targeted therapy. 1

Emergency Red Flags Requiring Immediate Intervention

• Anaphylaxis indicators: Respiratory compromise (dyspnea, wheeze, stridor), hypotension, or involvement of multiple organ systems beyond isolated lip swelling require immediate intramuscular epinephrine 0.3-0.5 mg and emergency transport 2
• Systemic symptoms: Fever with lip swelling suggests infectious etiology (bacterial abscess/cellulitis) requiring urgent evaluation and antibiotics 3, 4
• Rapid progression: Swelling developing over minutes to hours with urticaria or difficulty breathing indicates allergic reaction 2

Common Causes by Clinical Presentation

Allergic/Angioedema (Acute Onset, Minutes to Hours)

• Food-induced reactions: Most commonly peanut, tree nuts, milk, egg, fish, shellfish 2
• Drug hypersensitivity: Particularly ACE inhibitors, NSAIDs 2
• Insect stings: Especially in perioral region 2
• Clinical features: Swelling without erythema, pruritus, may have associated urticaria elsewhere 2

Infectious Causes (Subacute, Hours to Days)

• Bacterial infection (S. aureus): Presents with erythema, warmth, tenderness, possible fluctuance if abscess present 3, 4
• Angular cheilitis: Fungal (Candida) or bacterial infection at lip corners, often with fissuring 5, 6
• Herpes simplex: Vesicles progressing to crusting 5

Inflammatory/Chronic Causes (Days to Weeks)

• Contact cheilitis: Irritant or allergic reaction to lip products, foods, dental materials 5, 6
• Cheilitis glandularis: Chronic inflammation of labial salivary glands 6
• Granulomatous cheilitis: Part of orofacial granulomatosis, Crohn's disease, sarcoidosis, or Melkersson-Rosenthal syndrome 5, 6
• Plasma cell cheilitis: Reactive periorificial mucositis 6

Other Causes

• Trauma: Mechanical injury, thermal burns 2
• Cystic lesions: Dentigerous cysts (rare, slow-growing) 7
• Kawasaki disease (pediatric): Erythema, cracking, bleeding of lips with fever ≥5 days and other diagnostic criteria 2

Treatment Algorithm

Step 1: Rule Out Anaphylaxis (First 5 Minutes)

• If present: Respiratory symptoms, hypotension, multi-system involvement, or known allergen exposure with rapid onset
• Action: Administer epinephrine 0.3-0.5 mg IM in anterolateral thigh immediately, transport to emergency department 2
• Supportive care: Antihistamines and corticosteroids are adjunctive only, never replace epinephrine 2

Step 2: Assess for Infection (If Not Anaphylaxis)

• Clinical indicators: Fever, localized warmth, erythema, tenderness, purulent drainage, fluctuance 3, 4
• Imaging: Consider CT or ultrasound if abscess suspected 3
• Action for confirmed infection:
  • Obtain bacterial cultures 3
  • Surgical drainage if abscess present 3
  • Antibiotics: Cover MRSA (vancomycin IV or trimethoprim-sulfamethoxazole/clindamycin PO) for minimum 14 days 3, 4
  • Average hospital stay 4 days for severe cases 3

Step 3: Treat Non-Infectious Inflammatory Swelling

Immediate Symptomatic Management (All Cases)

• Apply white soft paraffin ointment every 2 hours to protect and moisturize lips 2, 1, 8
• Warm saline mouthwashes daily to reduce bacterial colonization 2, 1, 8
• Avoid alcohol-containing products which worsen pain and irritation 1, 8

Pain Control

• Benzydamine hydrochloride oral rinse/spray every 2-4 hours, especially before eating 2, 1, 8
• Viscous lidocaine 2% topically 3-4 times daily for severe pain 2, 9, 8

Anti-Inflammatory Treatment

• Topical corticosteroids (first-line for inflammatory cheilitis):
  • Betamethasone sodium phosphate 0.5 mg in 10 mL water as rinse-and-spit four times daily 2, 9
  • OR clobetasol propionate 0.05% mixed 1:1 with Orabase applied to affected areas twice daily 2, 9, 1
• Systemic corticosteroids for severe cases: Prednisone 30-60 mg daily for 1 week with taper 9

Treatment for Angular Cheilitis

• Combination antifungal + corticosteroid to address both Candida and inflammation 1
• Nystatin oral suspension 100,000 units four times daily for 1 week 2, 9, 1
• OR miconazole oral gel 5-10 mL four times daily for 1 week 2, 9, 1

Step 4: Manage Allergic Reactions (Non-Anaphylactic)

• Antihistamines: H1-blockers (diphenhydramine, cetirizine) for urticaria/mild angioedema 2
• Short course oral corticosteroids for extensive reactions 2
• Close observation for progression, especially first 2-4 hours 2
• Prescribe epinephrine auto-injector for future episodes if food/insect allergy confirmed 2

Critical Pitfalls to Avoid

• Never delay epinephrine in suspected anaphylaxis—fatal reactions associated with delayed administration 2
• Do not misidentify MRSA lip infection as angioedema—can result in serious morbidity/mortality 4
• Avoid chronic petroleum-based products alone—promote mucosal dehydration and increase infection risk 8
• Do not use antibiotics empirically for large local reactions to insect stings—these are allergic inflammation, not infection 2
• Never assume isolated lip swelling is benign—evaluate for systemic diseases (Crohn's, sarcoidosis, Kawasaki in children) 2, 5, 6

When to Reassess or Refer

• No improvement within 2 weeks of appropriate treatment warrants re-evaluation of diagnosis 1
• Recurrent episodes require allergy evaluation and consideration of systemic disease 2, 5
• Immunocompromised patients need more aggressive and prolonged therapy 1
• Chronic granulomatous cheilitis requires biopsy and evaluation for underlying systemic disease 5, 6