Azithromycin (Zithromax) vs Cefdinir (Omnicef)

Based on "Antibiotic and Chemotherapy"
written by Roger G. Finch

Azithromycin advantages over Cefdinir

  • Unlike cefdinir, azithromycin has excellent activity against atypical bacteria.
  • Generic azithromycin is less expensive than cefdinir.

Cefdinir advantages over Azithromycin

  • Cefdinir is very effective against penicillin-sensitive Pneumococcus and methicillin-sensitive Staphylococcus aureus.
  • Cefdinir suspension has good taste and smell.


Azithromycin Cefdinir
Brand names
• Zithromax®
• Z-PAK®
• Sumamed®
• Omnicef®
Drug class
• Antibiotic
Macrolide Cephalosporin, 3rd-generation
Dose formulations
• Tablets
• Capsules
• Powder for solution
• Oral suspension
• Capsules
• Oral suspension
FDA-approved indications
Acute otitis media
• Sinusitis
• Acute exacerbations of chronic bronchitis
• Community-acquired pneumonia
• Skin and skin structure infections (uncomplicated)
• Urethritis and cervicitis
• Genital ulcer disease
"Off-label" uses
• Gonococcal infections
• Lyme disease
• Acute uncomplicated cystitis
Mechanism of action
• Azithromycin inhibits bacterial protein synthesis.
• Its action is mainly bacteriostatic.
• Cefdinir inhibits bacterial cell wall synthesis.
• Its action is mainly bactericidal.
• 40 hours • 1.5 hours
Oral bioavailability
• 37% • 16-25%
• Iron containing products reduce cefdinir absorption by up to 80%
Metabolism, Elimination
• Excreted billiary,
mainly as unchanged drug in the feces. Urinary excretion is about 6%.
• Cefdinir doesn't undergo significant metabolism.
• Cefdinir is eliminated predominantly via the kidneys.
• Allergy to macrolide or ketolide antibiotics.
• History of hepatic dysfunction associated with prior use of azithromycin.
• Allergy to the cephalosporin antibiotics.
Side effects
• Diarrhea
• Nausea
• Abdominal pain
• Vomiting
• Diarrhea
• Abdominal pain, diarrhea,
• Nausea
• Cefdinir binds to iron in the gut, and may turn the stool read
Pregnancy category

Azithromycin vs Cefdinir for Otitis media

Both antibiotics are FDA-approved for the treatment of bacterial ear infection. Cefdinir is considered as a second line agent. The current pediatric guidelines do not recommend to use azithromycin to treat otitis media.

Cefdinir and azithromycin have comparable effectiveness in the treatment of acute otitis media1.

Results of multicenter, prospective, investigator-blinded study of children (between the ages of 6 months and 6 years) with a clinical diagnosis of AOM 1 Azithromycin Cefdinir
Regimen 10 mg/kg once daily on day 1 and 5 mg/kg once daily on days 2 through 5 7 mg/kg q12h for 5 days
Clinical cure rates 85% (149 patients of 176) 87% (151 patients of 174)
Clinical cure rates at the follow-up visit 86% 76%
Parents' satisfaction with regard to ease of use, taste, compliance, health care resource utilization, and missed days of work and day-care


Further reading


  • 1. Block SL, Cifaldi M, Gu Y, Paris MM. A comparison of 5 days of therapy with cefdinir or azithromycin in children with acute otitis media. Clin Ther. 2005 Jun;27(6):786-94. PubMed

Published: February 21, 2018
Last updated: February 21, 2018


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