Cefdinir Dose Calculator
Enter the patient age group, weight, and infection type to get the recommended cefdinir dose, dosing frequency, and treatment duration. For pediatric patients the calculator also shows how many millilitres of oral suspension to give per dose. A renal-impairment toggle applies the standard dose reduction for patients with a creatinine clearance below 30 mL/min.
What is cefdinir and how does it work?
Cefdinir (brand name Omnicef) is an oral third-generation cephalosporin antibiotic active against a broad range of gram-positive and gram-negative bacteria. It works by binding to penicillin-binding proteins and disrupting bacterial cell wall synthesis, which causes the bacterial cell to lyse and die. Because it is bactericidal rather than bacteriostatic, cefdinir is well suited for the short treatment courses used in outpatient practice. It is used to treat community-acquired pneumonia, acute exacerbations of chronic bronchitis, acute maxillary sinusitis, pharyngitis and tonsillitis, and uncomplicated skin infections. Cefdinir is available as 300 mg capsules for adults and as an oral suspension (125 mg/5 mL or 250 mg/5 mL) for children who cannot swallow capsules.
How cefdinir dosing is calculated
Adult and adolescent patients (aged 12 and older, or weighing more than 42 kg) receive a fixed dose of 300 mg every 12 hours. The total daily dose is therefore 600 mg regardless of body weight. Pediatric patients under 12 years who weigh 42 kg or less are dosed at 7 mg/kg every 12 hours, up to a maximum of 300 mg per dose. If the weight-based calculation exceeds 300 mg, the dose is capped and adult dosing applies. For oral suspension the volume required per dose is: dose in mg divided by the concentration in mg/mL (e.g. 125 mg/5 mL = 25 mg/mL, so a 140 mg dose requires 140/25 = 5.6 mL). Patients with severe renal impairment (creatinine clearance below 30 mL/min) receive a once-daily regimen: 300 mg for adults and 7 mg/kg up to 300 mg for children.
Suspension administration tips
Oral cefdinir suspension should be shaken well before each use. Store reconstituted suspension at room temperature (25 degrees C / 77 degrees F) and discard any unused portion after 10 days. Cefdinir can be given with or without food, which improves tolerability for children prone to nausea. Two important drug interactions affect absorption: iron-containing products (iron-fortified infant formula, iron supplements, and multivitamins with iron) and aluminum- or magnesium-containing antacids can reduce cefdinir absorption by up to 80%. Space cefdinir doses at least 2 hours apart from these products. Note that stool and urine may turn red or brick-colored because cefdinir and its metabolites bind to iron in the gut - this is harmless but should be mentioned to caregivers to avoid unnecessary alarm.
Renal impairment and other special populations
Cefdinir is primarily eliminated by the kidneys, so dose reduction is required when creatinine clearance falls below 30 mL/min. In adult patients the dose is reduced from 600 mg/day (300 mg twice daily) to 300 mg once daily. Pediatric patients with CrCl below 30 mL/min/1.73 m2 receive 7 mg/kg (up to 300 mg) once daily instead of twice daily. Hemodialysis patients typically receive 300 mg after each dialysis session. No adjustment is needed for mild to moderate renal impairment (CrCl 30 to 60 mL/min) or for hepatic impairment. Cefdinir is not approved for infants under 6 months of age due to limited safety data.
Cefdinir standard dosing by indication
| Indication | Adult dose | Pediatric dose | Duration |
|---|---|---|---|
| Community-acquired pneumonia | 300 mg q12h | 7 mg/kg q12h (max 300 mg) | 10 days |
| Acute bacterial exacerbation of chronic bronchitis | 300 mg q12h | 7 mg/kg q12h (max 300 mg) | 5-10 days |
| Acute maxillary sinusitis | 300 mg q12h | 7 mg/kg q12h (max 300 mg) | 10 days |
| Pharyngitis / tonsillitis | 300 mg q12h | 7 mg/kg q12h (max 300 mg) | 5-10 days |
| Uncomplicated skin infection | 300 mg q12h | 7 mg/kg q12h (max 300 mg) | 10 days |
Standard FDA-approved doses for adults and pediatric patients (under 12 years, up to 42 kg). For renal impairment (CrCl <30 mL/min), reduce to once-daily dosing at 300 mg (adult) or 7 mg/kg up to 300 mg (pediatric).
Frequently asked questions
What is the standard cefdinir dose for a child weighing 20 kg?
At 7 mg/kg every 12 hours, a 20 kg child receives 140 mg per dose, or 280 mg per day. Using a 125 mg/5 mL suspension, that works out to 5.6 mL per dose. Using the 250 mg/5 mL formulation, the volume is 2.8 mL per dose.
At what weight does a child switch to adult cefdinir doses?
When a child exceeds 42 kg, the weight-based dose would exceed 300 mg, so adult dosing (300 mg every 12 hours) applies instead. Most guidelines also use the adult dose for all patients aged 12 and older regardless of weight.
How should the dose change if my patient has kidney disease?
For patients with a creatinine clearance below 30 mL/min, cefdinir is given once daily rather than twice daily. Adults receive 300 mg every 24 hours instead of 300 mg every 12 hours. Pediatric patients receive 7 mg/kg (maximum 300 mg) every 24 hours. No adjustment is needed when CrCl is 30 mL/min or higher.
Why might a child's stool or urine turn red while taking cefdinir?
Cefdinir and its breakdown products can chelate (bind to) dietary iron in the gut, forming a red-colored compound. This can give stool a red or brick-red appearance and occasionally affect urine color. It is harmless and stops once the course is finished. Parents and caregivers should be warned in advance so they do not mistake it for blood.
How long does a cefdinir course typically last?
Most indications call for 5 to 10 days of treatment. Community-acquired pneumonia, acute sinusitis, and skin infections are treated for 10 days. Pharyngitis, tonsillitis, and acute exacerbations of chronic bronchitis may be treated for 5 days when a shorter course has been shown to be effective. Always complete the full prescribed course to minimize the risk of treatment failure and antibiotic resistance.
Can cefdinir be taken with food or milk?
Yes. Cefdinir can be taken with or without food and with or without milk. Food does not significantly affect overall absorption. The important restriction is to avoid taking cefdinir within 2 hours of iron-containing supplements, iron-fortified formula, or antacids containing aluminum or magnesium, as these can reduce absorption by up to 80%.