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What is Omnicef?
Omnicef (cefdinir) is a third-generation cephalosporin antibiotic used to treat a broad range of bacterial infections. It is often prescribed for upper respiratory tract infections such as sinusitis, pharyngitis, and bronchitis, as well as for skin infections and otitis media (ear infections). It is not effective against viral infections like the flu or common cold.
How It Works
Omnicef works by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs), which are essential for cell wall construction. Without a functioning wall, bacteria are unable to survive and are eliminated by the body’s immune system. This mechanism is bactericidal, meaning it kills the bacteria rather than merely inhibiting their growth.
Dosage Information
- Adults: 300mg twice daily or 600mg once daily for 5–10 days depending on infection type.
- Children: Weight-based dosing using oral suspension (typically 14mg/kg/day).
Omnicef may be taken with or without food. Do not take with iron-containing supplements, as absorption may be reduced.
Side Effects
Common side effects include diarrhea, nausea, abdominal pain, headache, and rash. These are typically mild and transient. Taking Omnicef with food may help reduce gastrointestinal discomfort.
Rare but serious side effects include C. difficile-associated diarrhea, allergic reactions, and liver enzyme elevation. Discontinue use and seek medical attention if you experience persistent diarrhea, hives, or swelling.
Warnings & Interactions
Omnicef should not be used in patients with known allergies to cephalosporins or penicillin due to potential cross-reactivity. Use caution in patients with renal impairment; dosage adjustment may be required.
Avoid taking Omnicef with antacids or iron supplements within 2 hours of a dose. These substances can interfere with drug absorption and reduce effectiveness.
Only buy Omnicef online through certified U.S. telehealth providers that require a prescription and verify your condition appropriately.
Frequently Asked Questions
Omnicef is used to treat bacterial infections like sinusitis, bronchitis, ear infections, and some skin infections.
Yes. Omnicef can be purchased from certified U.S. pharmacies and telehealth providers with a valid prescription.
Most patients feel improvement within 1–3 days, but it’s important to finish the full prescribed course.
Yes, cefdinir is the generic form and is widely available online and at local pharmacies.
Yes. It can be taken with or without food, though taking with food may reduce stomach upset.
Medical Disclaimer
This website provides informational overviews of medications and does not offer medical advice, diagnosis, or treatment. Always consult a licensed healthcare provider before starting or changing any medication.
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This page was last medically reviewed: June 2025
Take Omnicef only as prescribed. Complete the full course even if symptoms improve to prevent antibiotic resistance.