Calculate cefdinir (Omnicef) dosage for pediatric and adult patients by weight, indication, and renal function with suspension volume conversion.
Cefdinir (brand name Omnicef) is a third-generation oral cephalosporin antibiotic widely prescribed for common bacterial infections in children and adults. It is FDA-approved for acute otitis media, acute maxillary sinusitis, pharyngitis/tonsillitis, community-acquired pneumonia, and uncomplicated skin infections. Pediatric dosing is weight-based at 7 mg/kg twice daily (BID) or 14 mg/kg once daily (QD), with a maximum of 600 mg/day. Adults receive a fixed dose of 300 mg BID or 600 mg QD.
This cefdinir dosage calculator simplifies the process of determining the correct dose based on patient weight, age, chosen indication, and formulation concentration. It automatically converts milligram doses to suspension volumes for the common 125 mg/5 mL and 250 mg/5 mL oral suspensions, estimates the number of bottles needed for the full treatment course, and applies renal dose adjustments when creatinine clearance falls below 30 mL/min.
Accurate antibiotic dosing is critical for therapeutic success and minimizing resistance. Under-dosing cefdinir can lead to treatment failure and promote resistant bacterial strains, while over-dosing increases the risk of gastrointestinal side effects like diarrhea — a known issue with cefdinir, especially in young children. Our calculator includes preset weight ranges for common pediatric ages, indication-specific treatment durations, and a comprehensive reference table for quick bedside verification.
Calculating cefdinir doses by hand is error-prone, especially when converting between mg/kg doses and suspension volumes at different concentrations. Our calculator instantly handles the weight-based math, applies renal adjustments, selects the correct treatment duration per indication, and estimates the number of suspension bottles needed for the full course — saving time and reducing dosing errors at the prescribing and dispensing stages.
Pediatric dose: mg per dose = weight (kg) × 7 mg/kg (BID) or weight (kg) × 14 mg/kg (QD). Maximum daily dose = 600 mg. Adult dose: 300 mg BID or 600 mg QD. Renal adjustment: if CrCl < 30 mL/min, reduce dose by 50%. Suspension volume (mL) = (dose in mg ÷ concentration in mg) × 5 mL.
Result: 105 mg (4.2 mL) twice daily for 5 days
A 15 kg child: 15 × 7 = 105 mg per dose BID. Using 125 mg/5 mL suspension: (105 ÷ 125) × 5 = 4.2 mL per dose. For acute otitis media, the standard course is 5 days, totaling 1,050 mg over the full treatment.
Cefdinir belongs to the third-generation cephalosporin class and provides broad-spectrum activity against gram-positive organisms like Streptococcus pneumoniae and Streptococcus pyogenes, as well as gram-negative pathogens including Haemophilus influenzae and Moraxella catarrhalis. Its oral bioavailability is approximately 16–25%, with peak plasma concentrations reached 2–4 hours after dosing. The elimination half-life is about 1.7 hours, but its bacterial killing persists longer due to the time-dependent nature of cephalosporin activity.
The FDA-approved indications for cefdinir include acute bacterial otitis media (5 days or 10 days), acute maxillary sinusitis (10 days), pharyngitis/tonsillitis (5–10 days), community-acquired pneumonia (10 days), and uncomplicated skin and skin-structure infections (10 days). Multiple randomized controlled trials have demonstrated non-inferiority of cefdinir to amoxicillin-clavulanate for otitis media and to penicillin V for pharyngitis. The once-daily regimen has shown equivalent clinical cure rates to twice-daily dosing in pediatric otitis media studies.
In patients with significant renal impairment (CrCl < 30 mL/min), cefdinir clearance is reduced and the dose should be halved. Hemodialysis removes approximately 63% of cefdinir, so supplemental dosing after dialysis sessions is recommended. Cefdinir has not been studied extensively in neonates and is not typically used in infants under 6 months of age. During pregnancy, cefdinir is classified as Category B — animal studies show no fetal harm, but there are no adequate human studies. It is excreted in breast milk in small amounts.
The standard pediatric dose is 7 mg/kg given twice daily or 14 mg/kg given once daily, up to a maximum of 600 mg per day. Both regimens have similar efficacy for most indications.
Yes, cefdinir's pharmacokinetics support once-daily dosing at 14 mg/kg for most indications. Once-daily dosing improves adherence, especially in children, though some clinicians prefer BID for more severe infections.
For patients with creatinine clearance below 30 mL/min, reduce the dose by 50%. For patients on hemodialysis, give 300 mg (or 7 mg/kg for children) every other day, administered after the dialysis session.
Cefdinir can form a non-absorbable complex with iron (from iron-fortified formula or supplements), producing reddish or brick-colored stools. This is harmless and not a sign of bleeding. Separate iron products from cefdinir by 2 hours.
The maximum adult dose is 600 mg per day, given as either 300 mg twice daily or 600 mg once daily. This ceiling also applies to pediatric patients once the weight-based calculation exceeds 600 mg/day.
Reconstituted cefdinir oral suspension should be stored at room temperature (20–25°C / 68–77°F) and used within 10 days. Shake well before each dose. Discard any remaining suspension after 10 days.
Cefdinir has approximately a 1–2% cross-reactivity rate with penicillin allergy. It is generally considered safe for patients with mild penicillin allergy but should be avoided in those with a history of severe immediate-type (anaphylaxis) reactions to penicillins.