Cefdinir Dosage Calculator
This tool is for educational and informational purposes only. It does not replace professional medical advice, diagnosis, or treatment. Always consult your doctor or pharmacist before administering any medication.
Cefdinir Dosage Calculator
For infants under 6 months, cefdinir is not FDA-approved. Consult a pediatrician.
Children ≥43 kg (≈95 lbs) automatically receive adult dosing.
Enter Patient Details
Select age group, enter weight, choose the indication and formulation to calculate the recommended cefdinir dose.
Important
This calculator is provided for general information only and is not medical advice, diagnosis, or treatment. Results are estimates based on population averages and cannot account for your individual circumstances. Speak to a qualified healthcare professional before acting on anything you read here.
Weight-based pediatric and adult dosing with suspension volume and renal adjustment
Cefdinir, sold under the brand name Omnicef, is a third-generation oral cephalosporin antibiotic widely prescribed for a range of common bacterial infections in both adults and children. It is available as capsules (300 mg) for adults and as an oral suspension in two concentrations — 125 mg/5 mL and 250 mg/5 mL — for pediatric patients. Because cefdinir is dosed by body weight in children, and because dosing rules change depending on the infection being treated, the renal function of the patient, and whether once-daily or twice-daily dosing is preferred, caregivers and patients often find dosing complex to navigate without assistance. Our Cefdinir Dosage Calculator brings together the complete FDA-approved dosing framework into a single, easy-to-use tool. Whether you are a parent trying to understand how many milliliters of suspension to give your child for an ear infection, or a caregiver caring for an adult with a chronic bronchitis flare, this calculator provides a clear, structured breakdown of the recommended dose, volume or capsule count, dosing frequency options, and treatment duration — all in one place. The calculator supports both pediatric patients aged six months through twelve years and adults aged thirteen and older. For children, it automatically applies the weight-based dosing formula of 7 mg per kilogram per dose for twice-daily (BID) regimens and 14 mg per kilogram per dose for once-daily (QD) regimens, capping the total daily dose at 600 mg regardless of weight — consistent with the FDA package insert for Omnicef. Children weighing 43 kilograms (approximately 95 pounds) or more are automatically switched to the fixed adult dosing regimen of 300 mg BID or 600 mg QD, which is the standard clinical transition point. Not all cefdinir dosing regimens are interchangeable. The calculator enforces the critical clinical constraint that once-daily dosing is NOT appropriate for Community-Acquired Pneumonia (CAP) or uncomplicated skin and skin structure infections (SSIs). For these indications, only the BID regimen has been studied and proven effective. For other indications such as sinusitis, pharyngitis/tonsillitis, and acute exacerbation of chronic bronchitis (AECB), the calculator displays both BID and QD results side-by-side so prescribers and patients can see the equivalent options at a glance. Renal impairment significantly affects cefdinir dosing. For patients with a creatinine clearance below 30 mL/min, the total daily dose is reduced to 300 mg once daily for adults, or 7 mg/kg once daily (up to 300 mg) for children. Patients on hemodialysis receive 300 mg (or 7 mg/kg for children) every other day, with a supplemental dose after each dialysis session. The calculator surfaces these renal-adjusted outputs clearly, with color-coded notices to alert users to the modified regimen. Beyond the core dose calculation, the tool offers several practical features. A visual safety bar shows the calculated daily dose as a percentage of the 600 mg maximum, using color coding to highlight regimens that approach or reach the daily cap. For suspension formulations, a bottle duration estimator calculates how many days a standard 60 mL or 100 mL bottle will last at the calculated dose and frequency — a highly practical detail for caregivers managing refills. The tool also displays the total number of doses needed to complete the full antibiotic course, reinforcing the importance of course completion in antibiotic stewardship. Safety notes are integrated throughout. The calculator includes a prominent penicillin cross-reactivity reminder, noting that approximately 1–2% of patients with a true penicillin allergy may also react to cephalosporins such as cefdinir. Users are reminded to inform their healthcare provider of any penicillin or cephalosporin allergy history. A complete-course reminder is also included, as stopping antibiotics early — even when symptoms improve — is a leading contributor to treatment failure and antibiotic resistance. All results are prefaced with a clear medical disclaimer. This tool is designed to support, not replace, the clinical judgment of a licensed physician or pharmacist. Dosing for individual patients may differ based on factors not captured by this calculator, including comorbid conditions, concurrent medications, and local antibiotic resistance patterns. Always verify any calculated dose with a qualified healthcare provider before administration.
Understanding Cefdinir Dosing
What Is Cefdinir?
Cefdinir is a broad-spectrum, third-generation oral cephalosporin antibiotic. It works by inhibiting bacterial cell wall synthesis, leading to bacterial cell death. Cefdinir is active against many gram-positive bacteria including Staphylococcus aureus (non-MRSA) and Streptococcus species, as well as some gram-negative organisms such as Haemophilus influenzae, Moraxella catarrhalis, and Escherichia coli. It is FDA-approved for treating acute otitis media (middle ear infection), acute maxillary sinusitis, pharyngitis/tonsillitis caused by Streptococcus pyogenes, community-acquired pneumonia, uncomplicated skin infections, and acute exacerbation of chronic bronchitis. The oral suspension form (125 mg/5 mL and 250 mg/5 mL) is designed specifically for pediatric patients who cannot swallow capsules, while 300 mg capsules are used for adults and older adolescents.
How Is the Dose Calculated?
For pediatric patients (ages 6 months to 12 years, or until weight reaches 43 kg), the dose is weight-based: 7 mg per kilogram of body weight per dose for twice-daily (BID/Q12h) regimens, and 14 mg per kilogram per dose for once-daily (QD/Q24h) regimens. The total daily dose must not exceed 600 mg regardless of weight. Children weighing 43 kg or more automatically receive fixed adult doses: 300 mg BID or 600 mg QD. For adults, dosing is fixed at 300 mg every 12 hours or 600 mg every 24 hours, depending on indication. When using suspensions, the mL volume is calculated by dividing the mg dose by the suspension concentration: 25 mg/mL (for 125 mg/5 mL) or 50 mg/mL (for 250 mg/5 mL). For renal impairment with CrCl below 30 mL/min, the dose is reduced to 300 mg once daily for adults and 7 mg/kg once daily for children. Hemodialysis patients receive every-other-day dosing.
Why Correct Dosing Matters
Administering the correct dose of cefdinir is essential for two reasons: efficacy and safety. Under-dosing may result in treatment failure — the infection is not adequately cleared, symptoms persist, and drug-resistant bacteria may emerge. Over-dosing increases the risk of adverse effects such as gastrointestinal upset, diarrhea, and in rare cases, allergic reactions. For pediatric patients especially, dose accuracy by weight is critical because children's smaller bodies metabolize medications at different rates than adults. Renal dose adjustment is equally important: cefdinir is eliminated primarily through the kidneys, so patients with reduced renal function will accumulate the drug at standard doses, increasing toxicity risk. Course duration also matters — antibiotic courses are designed to eradicate the entire bacterial population, and stopping early — even when symptoms improve — leaves surviving bacteria that can cause relapse or resistance.
Limitations of This Calculator
This calculator implements the standard FDA-approved dosing guidelines for cefdinir as published in the Omnicef prescribing information. However, it cannot account for every patient-specific factor that may influence dosing decisions. It does not account for hepatic impairment (though cefdinir is primarily renally cleared), extreme obesity (where weight-based dosing may require adjustment), concurrent medications that interact with cefdinir, local bacterial resistance patterns that may make cefdinir an inappropriate choice, or patient-specific allergies and contraindications. The calculator requires exact body weight for accurate pediatric dosing — estimated or rounded weights may affect the calculated mL volume, particularly for very young children. The <6 months age restriction is enforced as a labeling note; users providing weight inputs for very young infants should consult a pediatrician directly. This tool is not a substitute for professional clinical judgment.
How to Use This Calculator
Select Age Group and Enter Weight
Choose Adult (≥13 yr) or Pediatric (6 mo–12 yr). Enter the patient's exact body weight and toggle between kilograms and pounds. For pediatric patients, accurate weight is critical because the dose is calculated per kilogram. Children weighing 43 kg or more will automatically receive adult fixed dosing.
Choose the Indication
Select the infection being treated from the dropdown. The indication determines both the dosing frequency options (BID only vs BID or QD) and the recommended treatment duration. Community-acquired pneumonia and skin infections require twice-daily dosing only; other indications allow once-daily dosing as an alternative.
Select Formulation and Renal Status
Choose the cefdinir formulation prescribed — 125 mg/5 mL suspension, 250 mg/5 mL suspension, or 300 mg capsule. Then select the patient's renal function status. If the patient has a creatinine clearance below 30 mL/min or is on hemodialysis, the calculator will automatically apply the appropriate dose reduction.
Review Results and Consult Your Pharmacist
The results show the dose per administration in mg and mL (or capsule count), frequency, course duration, and a safety bar comparing the daily dose to the 600 mg maximum. For suspensions, the bottle duration estimator shows how long a 60 mL or 100 mL bottle will last. Always confirm the calculated dose with your prescribing physician or pharmacist before administering.
Frequently Asked Questions
What is the standard cefdinir dose for a child with an ear infection?
For acute bacterial otitis media (middle ear infection), the FDA-approved pediatric dose is 7 mg/kg per dose given twice daily (every 12 hours) for 5 to 10 days, or 14 mg/kg once daily (every 24 hours) for 10 days. The maximum daily dose is 600 mg regardless of weight. For example, a child weighing 18 kg (40 lbs) would receive 126 mg per dose BID (about 5 mL of the 125 mg/5 mL suspension) or 252 mg once daily (about 10 mL of the 125 mg/5 mL suspension). Children weighing 43 kg or more receive adult fixed dosing of 300 mg BID or 600 mg QD.
Can cefdinir be given once daily instead of twice daily?
It depends on the indication. Once-daily (QD) dosing is a clinically acceptable alternative for acute otitis media, sinusitis, pharyngitis/tonsillitis, and acute exacerbation of chronic bronchitis (AECB). However, once-daily dosing has NOT been studied for community-acquired pneumonia or uncomplicated skin and skin structure infections. For those indications, only twice-daily (BID) dosing is FDA-approved and supported by clinical trial data. This calculator enforces that restriction automatically, displaying QD results only when the selected indication allows it.
How do I convert the mg dose to milliliters of suspension?
The conversion depends on which suspension strength you are using. For the 125 mg/5 mL suspension (equivalent to 25 mg per mL), divide the mg dose by 25 to get mL. For example, a 125 mg dose equals 5 mL. For the 250 mg/5 mL suspension (equivalent to 50 mg per mL), divide the mg dose by 50. For example, a 250 mg dose equals 5 mL. This calculator automatically performs this conversion and displays the mL volume for your selected formulation strength. Using the correct suspension strength when measuring is essential — always use the oral dosing syringe or measuring spoon provided with the medication, not a kitchen spoon.
Does cefdinir require dose adjustment for kidney problems?
Yes. Cefdinir is eliminated primarily by the kidneys, so patients with significantly reduced kidney function require dose reduction. For adults with a creatinine clearance (CrCl) below 30 mL/min, the recommended dose is 300 mg once daily rather than the standard 300 mg twice daily. For children with CrCl below 30 mL/min/1.73 m², the dose is 7 mg/kg once daily up to a maximum of 300 mg/day. Patients on hemodialysis receive a dose every other day (300 mg for adults; 7 mg/kg for children), with a supplemental dose given after each dialysis session. This calculator applies these renal adjustments automatically when you select CrCl <30 or Hemodialysis from the renal function dropdown.
Can patients with a penicillin allergy take cefdinir?
Cefdinir is a cephalosporin, not a penicillin, but there is a small risk of cross-reactivity between the two drug classes. Historically, the cross-reactivity rate was quoted at 10%, but more recent studies suggest the true rate for a serious allergic reaction is much lower — approximately 1 to 2% for patients with a confirmed true penicillin allergy. Patients with a history of a severe or anaphylactic reaction to penicillin should be evaluated carefully before receiving any cephalosporin. Patients with only a mild penicillin intolerance (such as rash without hives or breathing difficulty) may be at much lower risk. This decision should always be made by a licensed healthcare provider who can evaluate the full allergy history.
Why does my child's stool turn red or black when taking cefdinir?
Red or reddish-black discoloration of stools is a well-documented, benign side effect of cefdinir oral suspension. It occurs because the iron in certain foods — especially iron-fortified formula, iron supplements, and some baby foods — reacts with cefdinir in the gastrointestinal tract to form a red-colored compound. The stool discoloration is harmless and not a sign of gastrointestinal bleeding. If your child is taking iron-containing supplements or formula, you can reduce this effect by giving cefdinir at least two hours apart from iron-containing products. If you are uncertain whether the discoloration is medication-related or represents actual blood in the stool, contact your healthcare provider for guidance.