Information last reviewed: May 2026 — for educational purposes only.
Cefdinir, marketed as Omnicef, is a third-generation oral cephalosporin antibiotic effective against a broad range of gram-positive and gram-negative bacteria. It requires a prescription and is commonly prescribed for community-acquired respiratory tract infections, otitis media (ear infections), and uncomplicated skin infections in adults and children. Unlike some other cephalosporins, cefdinir is available as both capsules and an oral suspension, making it suitable for pediatric patients.
What Is Cefdinir (Omnicef) Used For?
Cefdinir is FDA-approved for the following indications:
- Acute otitis media (middle ear infection) — especially in children
- Acute sinusitis (bacterial rhinosinusitis)
- Community-acquired pneumonia — mild to moderate
- Acute exacerbations of chronic bronchitis
- Streptococcal pharyngitis and tonsillitis (strep throat)
- Uncomplicated skin and skin-structure infections
Cefdinir works by binding to penicillin-binding proteins (PBPs) in bacterial cell walls, inhibiting cell wall synthesis and causing cell lysis. It is stable against many beta-lactamases produced by common pathogens. Organisms covered include Streptococcus pneumoniae, Streptococcus pyogenes, Haemophilus influenzae, Moraxella catarrhalis, and Staphylococcus aureus (methicillin-susceptible strains only).
Is Cefdinir Available Over the Counter?
No. Cefdinir (Omnicef) is a prescription-only antibiotic in all markets where it is approved. It requires diagnosis and authorisation from a licensed prescriber. As a beta-lactam antibiotic, it carries a small risk of hypersensitivity reactions. Patients with penicillin allergy have an approximately 1–2% risk of cross-reactivity with cephalosporins like cefdinir; the prescriber should be informed of any penicillin allergy history.
Strengths and Formulations
- Omnicef / generic cefdinir 300 mg capsules — adult oral dose: 300 mg twice daily (BID) or 600 mg once daily (QD) for most indications; course length 5–10 days depending on indication
- Oral suspension 125 mg/5 ml — for children; the usual pediatric dose is 7 mg/kg once or twice daily depending on age and indication, not exceeding 14 mg/kg/day or 600 mg/day
A distinctive feature: cefdinir oral suspension can turn stools red or reddish-brown in infants and young children, especially if taken with iron-containing formula. This is a harmless interaction between cefdinir and iron — the red colouring is not blood.
Price of Generic Cefdinir
Generic cefdinir capsules and suspension are widely available in the US at low cost. A typical 10-day course of 300 mg capsules costs around $15–$25 with a discount card at major pharmacy chains. Brand-name Omnicef is rarely dispensed today due to generic availability. Costs vary by country and health system.
Frequently Asked Questions
Is cefdinir safe if I am allergic to penicillin?
A true allergy to penicillin does not automatically mean you cannot take cefdinir. The cross-reactivity rate between penicillins and cephalosporins is estimated at 1–2%, far lower than previously thought. However, patients with a history of severe anaphylactic reactions to penicillin should use cephalosporins with caution. Always inform your prescriber of any antibiotic allergy history before starting cefdinir.
Can cefdinir be taken with food?
Yes. Cefdinir can be taken with or without food. However, it should not be taken within 2 hours of iron supplements or iron-fortified foods, as iron can reduce absorption by up to 80%. Antacids containing aluminium or magnesium can also reduce absorption and should be separated by at least 2 hours.
Why is my child's stool red or reddish-brown while on cefdinir?
This is a known, harmless effect seen when cefdinir reacts with iron in infant formula or dietary iron. The compound formed produces a red discolouration in the stool. It is not blood and requires no action other than reassurance. If you are uncertain whether the discolouration is due to medication or something else, contact your healthcare provider.
Disclaimer: This page is for general informational purposes only and does not constitute medical advice. Always consult a licensed healthcare professional before taking any medication. See our full disclaimer.