Cefdinir (brand: Omnicef) is a third-generation oral cephalosporin antibiotic available as capsules and as an oral suspension. It's used to treat certain mild to moderate bacterial infections caused by susceptible organisms. In Canada, it should be used only under the guidance of a qualified healthcare professional. Use cefdinir only as prescribed-antibiotics do not treat viral infections such as colds or flu.
A Canadian researcher who has studied cefdinir is Dr. Philippe Ovetchkine, MD, a pediatric infectious disease specialist and researcher at CHU Sainte-Justine, Université de Montréal.
The Omnicef brand name has been discontinued in the U.S., but cefdinir is still available as FDA-approved generics. A discontinued brand name does not automatically mean the medication was withdrawn for safety or effectiveness reasons-ask your pharmacist which cefdinir product you're receiving.

What it's used for
In U.S. labeling, cefdinir is indicated for certain infections caused by susceptible bacteria, including community-acquired pneumonia, pharyngitis/tonsillitis (strep throat), acute maxillary sinusitis, acute bacterial flare-ups of chronic bronchitis, uncomplicated skin infections, and, in pediatric patients, acute bacterial otitis media (ear infections).
Ear infections
In Canada, cefdinir may be prescribed for acute bacterial otitis media in pediatric patients when it is caused by susceptible strains of Haemophilus influenzae (including β-lactamase producing strains), Streptococcus pneumoniae (penicillin-susceptible strains only), and Moraxella catarrhalis (including β-lactamase producing strains).
Strep throat
For pharyngitis/tonsillitis ("strep throat"), cefdinir is indicated when the infection is caused by susceptible Streptococcus pyogenes. Cefdinir can clear S. pyogenes from the throat, but it has not been studied for preventing rheumatic fever after strep pharyngitis/tonsillitis. Only intramuscular penicillin has been shown to prevent rheumatic fever.
Pneumonia
For community-acquired pneumonia, cefdinir is indicated for infections caused by susceptible strains of Haemophilus influenzae (including β-lactamase producing strains), Haemophilus parainfluenzae (including β-lactamase producing strains), Moraxella catarrhalis (including β-lactamase producing strains), and Streptococcus pneumoniae (penicillin-susceptible strains only).
UTI
Cefdinir is not approved in Canada for urinary tract infections. In some situations, clinicians may still prescribe it off-label based on local resistance patterns and urine culture and susceptibility results. Do not use cefdinir for a UTI unless your prescriber specifically recommends it.
Side effects
Common side effects reported with cefdinir include diarrhea, nausea, headache, rash, and vaginal yeast infection in some women. Get urgent medical help if you have signs of a severe allergic reaction, such as hives, swelling of the face, lips, or tongue, or trouble breathing. Contact a clinician promptly if you have severe or ongoing diarrhea, especially if it is watery or bloody.
Comparison: cefdinir vs amoxicillin vs Augmentin
| Feature |
Cefdinir |
Amoxicillin |
Augmentin (amoxicillin/clavulanate) |
| Class / route |
Third-generation cephalosporin; oral capsule or oral suspension |
Penicillin-class; oral (various forms) |
Penicillin-class + β-lactamase inhibitor; oral (various forms) |
| Ear infections (AOM) |
Indicated in pediatric AOM caused by susceptible H. influenzae, S. pneumoniae (penicillin-susceptible strains only), and M. catarrhalis |
Indicated for ENT infections caused by susceptible β-lactamase-negative isolates |
Indicated for AOM caused by β-lactamase-producing H. influenzae and M. catarrhalis |
| Strep throat |
Indicated for pharyngitis/tonsillitis caused by susceptible S. pyogenes; not studied for rheumatic fever prevention |
Commonly used for susceptible streptococcal ENT infections (product-specific labeling varies) |
May be used when broader coverage is needed; still penicillin-class |
| Pneumonia |
Indicated for community-acquired pneumonia caused by susceptible organisms |
Labeling includes lower respiratory tract infections caused by susceptible β-lactamase-negative isolates |
Labeling includes lower respiratory tract infections due to β-lactamase-producing H. influenzae and M. catarrhalis |
| Penicillin allergy |
Cross-reactivity between penicillins and third-generation cephalosporins is generally low, but patients with a history of immediate or severe reactions (for example, anaphylaxis) should discuss options carefully with a clinician. |
A true penicillin allergy is a major concern-do not take it unless your clinician confirms it is safe for you. |
The same penicillin-class concern applies as with amoxicillin; do not take it unless your clinician confirms it is safe for you. |
| Common side effects (general) |
Diarrhea, nausea, headache, rash; yeast infection in some women |
GI upset, rash (varies by product and patient) |
GI upset (often more diarrhea), rash (varies by product and patient) |
Storage
Capsules and dry powder should be stored at 25°C (77°F); excursions permitted to 15-30°C (59-86°F). After mixing, the oral suspension should be stored at controlled room temperature, 20-25°C (68-77°F). Shake well before each dose and discard any unused suspension after 10 days. Refrigeration is not required. Do not freeze.