What is the most effective antibiotic for treating cellulitis?

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Last updated: April 18, 2025 • View editorial policy

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

The best antibiotic for cellulitis is typically cephalexin (Keflex) at a dose of 500 mg taken orally four times daily for 5 days, as this duration has been shown to be sufficient for treatment 1. For patients with penicillin allergies, clindamycin 300-450 mg four times daily is an effective alternative. In more severe cases or for patients with risk factors for methicillin-resistant Staphylococcus aureus (MRSA), trimethoprim-sulfamethoxazole (Bactrim) or doxycycline may be added to the regimen, although coverage for non-purulent cellulitis is generally not recommended 2. The most common causative organisms of cellulitis are Streptococcus and Staphylococcus species, and these recommendations target these pathogens 3, 2. While taking antibiotics, patients should elevate the affected area, apply warm compresses, and monitor for spreading redness, increasing pain, fever, or streaking, which may indicate worsening infection requiring immediate medical attention. Some key points to consider when treating cellulitis include:

  • The majority of non-purulent, uncomplicated cases of cellulitis are caused by β-hemolytic streptococci or methicillin-sensitive Staphylococcus aureus 2
  • Microbiological diagnosis is often unobtainable due to poor sensitivity of culture specimens 3, 2
  • Local susceptibility patterns should guide empiric therapy 4
  • The evidence used in developing current guidelines has significant limitations, and further studies are needed to resolve treatment dilemmas 4

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