Can a wasp sting cause cellulitis?

Can a Wasp Sting Cause Cellulitis?

Wasp stings do not typically cause true bacterial cellulitis; the swelling and erythema that develop are almost always due to allergic inflammation from mediator release, not infection, and antibiotics are not indicated unless there is clear evidence of secondary bacterial infection. 1

Understanding the Mechanism

The extensive swelling, redness, and warmth that can occur after a wasp sting mimics cellulitis but represents a fundamentally different process:

• Large local reactions are IgE-mediated allergic responses that cause swelling extending from the sting site, typically peaking at 24-48 hours and lasting up to a week or more 1
• The swelling is caused by allergic inflammation and mediator release, not by bacterial infection 1
• This is a common misdiagnosis that leads to inappropriate antibiotic prescribing 1, 2

Clinical Presentation That Mimics Cellulitis

• Extensive erythema and swelling surrounding the sting site that persists for several days 1
• Accompanied by itching, pain, or both 1
• May include lymphangitis (which is also caused by mediator release, not infection) 1
• These large local reactions occur in 5-15% of the population 1

Appropriate Treatment (Not Antibiotics)

• Cold compresses to reduce local pain and swelling 1
• Oral antihistamines to reduce itching and pain 1
• Oral corticosteroids for severe large local reactions, though definitive proof through controlled studies is lacking 1
• Antibiotics are NOT indicated unless there is clear evidence of secondary bacterial infection 1

When True Secondary Infection Occurs (Rare)

• Secondary bacterial infection is possible but uncommon 1
• Only prescribe antibiotics when there is clear evidence of secondary infection (purulent drainage, fever, progressive worsening beyond 48-72 hours despite anti-inflammatory treatment) 1, 3
• One case report documented eosinophilic cellulitis (Wells syndrome) after honeybee sting that required systemic steroids, not antibiotics 4

Critical Pitfall to Avoid

The most common error is mistaking allergic swelling and lymphangitis for bacterial cellulitis and inappropriately prescribing antibiotics instead of focusing on anti-inflammatory treatment. 1, 2 This misdiagnosis occurs frequently because the clinical appearance can be nearly identical to true cellulitis 1, 5.

When to Escalate Care

• Monitor for signs of systemic reaction (difficulty breathing, widespread urticaria, hypotension) which require immediate epinephrine administration 1
• Consider vascular compromise if there is increasing pain, numbness, coolness of extremity, or color changes requiring emergency evaluation 3
• Patients with large local reactions have up to 10% risk of eventual systemic reaction and may benefit from allergist referral 1