Recommended Antibiotic for Cellulitis in Pregnancy
For a pregnant person with uncomplicated cellulitis, use oral beta-lactam monotherapy—specifically cephalexin 500 mg four times daily, amoxicillin 500 mg three times daily, or penicillin—for 5 days if clinical improvement occurs. 1, 2
First-Line Treatment Selection
Beta-lactam antibiotics are the standard of care for typical cellulitis and are safe during pregnancy:
- Cephalexin 500 mg orally four times daily is an excellent first-line choice, providing robust streptococcal and methicillin-sensitive S. aureus coverage 1
- Amoxicillin 500 mg orally three times daily is equally effective and safe throughout pregnancy 1, 3
- Penicillin V 250-500 mg orally four times daily offers excellent streptococcal coverage 1
- Dicloxacillin 250-500 mg every 6 hours is another beta-lactam option 1
Penicillins and cephalosporins are first-line antibiotics during pregnancy with well-established safety profiles, and more commonly used agents should be prioritized. 3
Treatment Duration
- Treat for exactly 5 days if clinical improvement occurs (reduced warmth, tenderness, and erythema) 1
- Extend treatment only if symptoms have not improved within this 5-day timeframe 1
- Traditional 7-14 day courses are unnecessary for uncomplicated cases 1
When MRSA Coverage Is Needed
MRSA coverage is not routinely necessary for typical nonpurulent cellulitis, even in pregnancy. 1, 4 However, add MRSA-active therapy if:
- Penetrating trauma is present 1
- Purulent drainage or exudate exists 1
- Patient has documented MRSA infection elsewhere 1
- Failure to respond to beta-lactam therapy after 48 hours 1
Safe MRSA-Active Options in Pregnancy
Clindamycin 300-450 mg orally every 6 hours is the preferred MRSA-active agent in pregnancy, as it covers both streptococci and MRSA without requiring combination therapy. 1, 3
Antibiotics to AVOID in Pregnancy
- Doxycycline is contraindicated (pregnancy category D) and should never be used 1, 3
- Tetracyclines are contraindicated after the fifth week of pregnancy due to tooth discoloration and bone growth effects 1, 3
- Trimethoprim-sulfamethoxazole should be avoided, particularly in the first trimester and near term 3
- Fluoroquinolones (levofloxacin, moxifloxacin) are contraindicated as a precautionary measure 3
- Aminoglycosides should not be prescribed due to nephrotoxicity and ototoxicity 3
Severe Cellulitis Requiring Hospitalization
For pregnant patients with systemic toxicity, hypotension, altered mental status, or suspected necrotizing infection:
- Cefazolin 1-2 g IV every 8 hours is the preferred IV beta-lactam 1
- Add vancomycin 15-20 mg/kg IV every 8-12 hours if MRSA coverage is needed 1
- For suspected necrotizing fasciitis, use vancomycin plus piperacillin-tazobactam 3.375-4.5 g IV every 6 hours 1
Essential Adjunctive Measures
- Elevate the affected extremity above heart level to promote drainage 1
- Examine and treat interdigital toe spaces for tinea pedis, as this reduces recurrence risk 1
- Address predisposing conditions including venous insufficiency, lymphedema, and chronic edema 1, 5
Critical Pitfalls to Avoid
- Do not reflexively add MRSA coverage simply because community MRSA exists—beta-lactam monotherapy succeeds in 96% of cases 1, 4
- Do not use doxycycline or tetracyclines at any point during pregnancy 1, 3
- Do not extend treatment beyond 5 days if clinical improvement has occurred—longer courses provide no benefit 1
- Do not use combination therapy (e.g., TMP-SMX plus beta-lactam) for typical cellulitis in pregnancy when safer single-agent options exist 1, 3
Key Evidence Supporting This Approach
Beta-lactam monotherapy achieves 96% success rates even in high MRSA prevalence settings, confirming that MRSA coverage is usually unnecessary. 1, 4 The causative organisms in cellulitis are predominantly β-hemolytic streptococci and methicillin-sensitive S. aureus when identified. 4, 6 Penicillins and cephalosporins have well-established safety during all trimesters of pregnancy and should be prioritized. 3