Cellulitis: Symptoms and Medication
Clinical Presentation
Cellulitis presents as a diffuse, superficial, spreading skin infection characterized by erythema, warmth, tenderness, and swelling without pus collection. 1, 2
- The infection involves the deep dermis and subcutaneous tissue 2
- Patients typically experience severe pain and systemic symptoms 3
- The affected area shows expanding erythema with associated edema 2, 4
- Purulent drainage or abscess formation is NOT typical of cellulitis - if present, this represents a different type of skin infection requiring different management 1
Recommended Antibiotic Treatment
First-Line Therapy for Uncomplicated Cellulitis
For nonpurulent cellulitis, use antibiotics active against streptococci, as β-hemolytic streptococci are the predominant pathogens. 1
Recommended oral antibiotics include: 1, 5
Duration of Treatment
A 5- to 6-day course of antibiotics is recommended for patients with uncomplicated cellulitis who can self-monitor and have close follow-up. 1
- Treatment should be extended only if the infection has not improved after 5 days 1, 5
- The NICE guideline supports 5 to 7 days as adequate duration 1
- Multiple RCTs demonstrate that shorter courses (5-6 days) achieve similar clinical outcomes to longer courses (10-14 days) 1
When to Add MRSA Coverage
Do NOT routinely add MRSA coverage for typical nonpurulent cellulitis. 5, 6, 7
Add MRSA-active antibiotics (such as trimethoprim-sulfamethoxazole or doxycycline) ONLY in these specific situations: 1, 5
- Cellulitis associated with penetrating trauma 1, 5
- Evidence of MRSA infection elsewhere on the body 1, 5
- Nasal colonization with MRSA 1
- Injection drug use 1, 5
- Systemic inflammatory response syndrome (SIRS) 1, 5
- Purulent drainage present 5
The evidence strongly supports this approach: Two large randomized controlled trials demonstrated that adding trimethoprim-sulfamethoxazole to cephalexin provided no benefit over cephalexin alone for uncomplicated cellulitis. 6, 7 In the most recent trial of 496 patients, clinical cure occurred in 83.5% with combination therapy versus 85.5% with cephalexin alone (no significant difference). 7
Adjunctive Measures
Elevate the affected area to promote drainage of edema and inflammatory substances. 5
Consider adding prednisone 40 mg daily for 7 days in non-diabetic adults to reduce inflammation and hasten resolution. 5
When to Hospitalize
Most patients can be treated as outpatients. 5
Consider hospitalization if any of the following are present: 5
- Systemic inflammatory response syndrome (SIRS) 5
- Altered mental status 5
- Hemodynamic instability 5
- Concern for deeper or necrotizing infection 5
- Poor adherence to therapy 5
- Severe immunocompromise 5
Prevention of Recurrence
Identify and treat predisposing conditions at the initial visit: 5, 4
For patients with frequent recurrences (3-4 episodes per year), consider prophylactic antibiotics such as oral penicillin, erythromycin, or intramuscular benzathine penicillin. 5
Critical Pitfalls to Avoid
Do not extend antibiotic treatment beyond 5-6 days if clinical improvement has occurred - this increases antibiotic resistance without improving outcomes. 1, 5
Do not automatically add MRSA coverage for typical nonpurulent cellulitis - research demonstrates no benefit and increases unnecessary antibiotic exposure. 5, 6, 7
Do not obtain blood cultures or tissue aspirates routinely - these are not needed for typical cases of cellulitis. 5