Drug Monograph
Cefdinir
Formerly marketed as Omnicef
Pharmacokinetic Profile
Half-Life
1.7 h (±0.6)
Metabolism
Not appreciably metabolized
Protein Binding
60–70%
Bioavailability
21% (caps) / 25% (susp)
Volume of Distribution
0.35 L/kg (adults)
Clinical Information
Drug Class
3rd-Gen Cephalosporin
Available Doses
300 mg cap; 125 & 250 mg/5 mL susp
Route
Oral
Renal Adjustment
Yes — CrCl <30 mL/min
Hepatic Adjustment
Not required
Pregnancy
Category B
Lactation
Not detected in breast milk (600 mg dose)
Schedule
Rx only (not controlled)
Generic Available
Yes
Indications
| Indication | Approved Population | Therapy Type | Status |
|---|---|---|---|
| Community-acquired pneumonia | Adults & adolescents | Monotherapy | FDA Approved |
| Acute exacerbation of chronic bronchitis | Adults & adolescents | Monotherapy | FDA Approved |
| Acute maxillary sinusitis | Adults, adolescents & children ≥6 months | Monotherapy | FDA Approved |
| Pharyngitis / tonsillitis | Adults, adolescents & children ≥6 months | Monotherapy | FDA Approved |
| Uncomplicated skin & skin-structure infections | Adults, adolescents & children ≥6 months | Monotherapy | FDA Approved |
| Acute bacterial otitis media | Children ≥6 months | Monotherapy | FDA Approved |
Cefdinir covers penicillin-susceptible Streptococcus pneumoniae, Haemophilus influenzae (including beta-lactamase producers), Moraxella catarrhalis, Streptococcus pyogenes, and methicillin-susceptible Staphylococcus aureus. It is inactive against MRSA, Pseudomonas, and Enterococcus species. Guidelines recommend cefdinir as an alternative to amoxicillin or amoxicillin-clavulanate in patients with non-severe penicillin allergy for otitis media and sinusitis (AAP/IDSA).
Off-Label Uses
Uncomplicated urinary tract infections (UTIs): Cefdinir is sometimes prescribed off-label for acute uncomplicated cystitis, particularly in pediatric patients. Evidence quality: Low — limited prospective data; alternative agents with established UTI activity are generally preferred in adults.
Dosing
Adults & Adolescents
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Community-acquired pneumonia | 300 mg BID | 300 mg BID | 600 mg/day | 10-day course; must use BID for pneumonia Once-daily not studied for this indication |
| Acute exacerbation of chronic bronchitis | 300 mg BID or 600 mg daily | Same as starting | 600 mg/day | BID: 5–10 days; QD: 10 days Once-daily regimen requires full 10-day course |
| Acute maxillary sinusitis | 300 mg BID or 600 mg daily | Same as starting | 600 mg/day | 10-day course IDSA notes variable S. pneumoniae susceptibility; not recommended as empiric monotherapy for sinusitis |
| Streptococcal pharyngitis / tonsillitis | 300 mg BID or 600 mg daily | Same as starting | 600 mg/day | BID: 5–10 days; QD: 10 days Does not prevent rheumatic fever; only IM penicillin has proven efficacy for this |
| Uncomplicated skin & skin-structure infections | 300 mg BID | 300 mg BID | 600 mg/day | 10-day course; must use BID for skin infections Once-daily not studied for this indication |
Pediatric Patients (6 Months–12 Years)
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| Acute otitis media | 7 mg/kg BID or 14 mg/kg daily | Same as starting | 600 mg/day | BID: 5–10 days; QD: 10 days Alternative for penicillin-allergic patients (AAP) |
| Acute maxillary sinusitis | 7 mg/kg BID or 14 mg/kg daily | Same as starting | 600 mg/day | 10-day course |
| Streptococcal pharyngitis / tonsillitis | 7 mg/kg BID or 14 mg/kg daily | Same as starting | 600 mg/day | BID: 5–10 days; QD: 10 days |
| Uncomplicated skin & skin-structure infections | 7 mg/kg BID | Same as starting | 600 mg/day | 10-day course; must use BID Once-daily not studied for skin infections |
Renal Impairment & Hemodialysis
| Clinical Scenario | Starting Dose | Maintenance Dose | Maximum Dose | Notes |
|---|---|---|---|---|
| CrCl ≥30 mL/min (adults) | No adjustment | Standard dosing | 600 mg/day | Monitor for accumulation in CrCl 30–60 range |
| CrCl <30 mL/min (adults) | 300 mg once daily | 300 mg once daily | 300 mg/day | Significant accumulation expected (AUC increased ~6-fold) |
| CrCl <30 mL/min/1.73 m2 (pediatric) | 7 mg/kg once daily | 7 mg/kg once daily | 300 mg/day | Use Schwartz formula to estimate CrCl |
| Chronic hemodialysis | 300 mg (adult) or 7 mg/kg (peds) every other day | Same; supplemental dose after each session | 300 mg/day equivalent | Dialysis removes 63% of cefdinir over 4 hours; give supplemental dose post-dialysis |
Clinical Pearl: Once-Daily vs Twice-Daily Dosing
For most indications, once-daily dosing (600 mg adults; 14 mg/kg pediatric) over 10 days has been shown to be as effective as twice-daily regimens. However, once-daily dosing has not been studied for pneumonia or skin infections — these indications require BID administration. Patients who have difficulty with twice-daily adherence can use once-daily dosing for pharyngitis, sinusitis, otitis media, and bronchitis.
Pharmacology
Mechanism of Action
Cefdinir is an extended-spectrum, semisynthetic third-generation cephalosporin that exerts bactericidal activity by binding to penicillin-binding proteins (PBPs) in the bacterial cell wall, inhibiting the final transpeptidation step of peptidoglycan synthesis. This leads to cell wall instability and bacterial lysis. Cefdinir demonstrates stability against hydrolysis by many beta-lactamase enzymes, which accounts for its activity against beta-lactamase-producing strains of H. influenzae, M. catarrhalis, and S. aureus. However, it is inactivated by certain extended-spectrum beta-lactamases and AmpC enzymes, rendering it inactive against Enterobacter, Pseudomonas, MRSA, and penicillin-resistant pneumococci.
ADME Profile
| Parameter | Value | Clinical Implication |
|---|---|---|
| Absorption | Tmax 2–4 h; bioavailability 21% (capsules), 25% (suspension); food effect minimal (10–16% reduction with high-fat meal for capsules) | Can be given without regard to meals; suspension has slightly higher bioavailability than capsules |
| Distribution | Vd 0.35 L/kg (adults), 0.67 L/kg (pediatric); protein binding 60–70%; penetrates middle ear fluid, tonsils, sinus tissue, bronchial mucosa | Achieves therapeutic concentrations at common infection sites; no CSF penetration data available |
| Metabolism | Not appreciably metabolized; activity due to parent drug; no CYP involvement | Very low drug interaction potential via CYP enzymes; no hepatic dose adjustment needed |
| Elimination | t½ 1.7 h; primarily renal excretion; 11.6–18.4% recovered unchanged in urine; renal clearance 2.0 mL/min/kg | Short half-life requires BID dosing for some indications; dose reduction needed in severe renal impairment (CrCl <30 mL/min) |
Side Effects
≥10%
Very Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Diarrhea | 15% (adults); 8% (peds) | Most common adverse event; rate rises to 17% in children ≤2 years; usually mild and self-limiting; consider antibiotic-associated diarrhea management if persistent |
1–10%
Common
| Adverse Effect | Incidence | Clinical Note |
|---|---|---|
| Vaginal moniliasis | 4% of women | Typical of broad-spectrum cephalosporins; counsel patients about symptoms of vaginal yeast infection |
| Nausea | 3% | Taking with food may reduce GI discomfort |
| Rash (pediatric) | 3% (peds); 0.9% (adults) | Predominantly diaper rash in children ≤2 years (8% in that age group); distinguish from true drug allergy |
| Headache | 2% | Usually mild and transient |
| Abdominal pain | 1% (adults); 0.8% (peds) | Monitor for escalating symptoms that may suggest C. difficile colitis |
| Vaginitis | 1% of women | Related to disruption of normal vaginal flora |
| Vomiting (pediatric) | 1% (peds); 0.7% (adults) | More common in younger children; ensure adequate hydration |
Serious
Serious (Regardless of Frequency)
| Adverse Effect | Estimated Frequency | Typical Onset | Required Action |
|---|---|---|---|
| Anaphylaxis | Rare | Minutes to hours after first or subsequent doses | Discontinue immediately; administer epinephrine and supportive care; permanent discontinuation |
| Clostridioides difficile-associated diarrhea (CDAD) | Uncommon | During or up to 2 months after therapy | Discontinue cefdinir if confirmed; stool testing for C. difficile toxin; treat with oral vancomycin or fidaxomicin |
| Stevens-Johnson syndrome / toxic epidermal necrolysis | Very rare | 1–3 weeks after initiation | Immediate discontinuation; dermatology consultation; supportive care; never re-challenge |
| Serum sickness-like reaction | Rare | 7–21 days after initiation | Discontinue; anti-inflammatory treatment as needed; avoid cephalosporin re-challenge |
| Acute hepatitis / hepatic failure | Very rare | Days to weeks after initiation | Discontinue immediately; check LFTs; hepatology referral if values significantly elevated or jaundice present |
| Hemolytic anemia | Very rare | Variable | Discontinue; direct Coombs test; hematology consultation if severe |
| Seizures (class effect) | Very rare | Usually with renal impairment and excessive dosing | Discontinue; anticonvulsant therapy if indicated; ensure correct renal dosing |
Discontinuation
Discontinuation Rates
Adults & Adolescents
3%
Top reasons: Diarrhea, nausea (GI disturbances). Rash accounted for 0.4% of all discontinuations.
Pediatric Patients
2%
Top reasons: Diarrhea (primary cause). Rash accounted for 0.2% of discontinuations.
| Reason for Discontinuation | Incidence | Context |
|---|---|---|
| GI disturbances (diarrhea, nausea) | ~2.5% (adults) | N = 5,093 adult/adolescent patients in pivotal trials; most events were mild |
| Rash | 0.4% (adults); 0.2% (peds) | Distinguish true drug allergy from non-specific rash, particularly diaper dermatitis in infants |
Management: Diarrhea
Diarrhea is the most frequent adverse event with cefdinir. Mild diarrhea typically resolves after completing the antibiotic course. Do not empirically treat with anti-motility agents until C. difficile has been excluded, particularly if stools become watery, bloody, or are accompanied by fever. Probiotics may be considered adjunctively, though evidence is modest. Red-colored stools can occur when cefdinir is co-administered with iron-containing products — this is a harmless chemical complex, not blood.
Drug Interactions
Cefdinir is not metabolized via the cytochrome P450 system, so CYP-mediated interactions are negligible. The most clinically significant interactions involve drugs or supplements that impair oral absorption or reduce renal clearance of cefdinir.
Major
Iron supplements (therapeutic dose, 60 mg elemental iron)
MechanismChelation forming nonabsorbable cefdinir-iron complex in the GI tract
EffectReduces cefdinir absorption by up to 80%; may also cause reddish stools
ManagementSeparate administration by at least 2 hours; iron-fortified infant formula does not significantly interact
FDA PI
Major
Aluminum/Magnesium-containing antacids
MechanismReduced absorption via chelation and increased gastric pH
EffectReduces cefdinir Cmax and AUC by approximately 40%
ManagementSeparate administration by at least 2 hours before or after the antacid
FDA PI
Moderate
Probenecid
MechanismInhibits renal tubular secretion of cefdinir
EffectApproximately doubles cefdinir AUC; increases Cmax by 54% and prolongs half-life by 50%
ManagementMonitor for increased side effects if co-administered; dose reduction may be necessary
FDA PI
Moderate
Aminoglycosides (e.g., gentamicin, amikacin)
MechanismAdditive nephrotoxicity (class effect of cephalosporins)
EffectPotential increased nephrotoxic and ototoxic risk
ManagementMonitor renal function closely if combination is necessary
Lexicomp
Moderate
Live bacterial vaccines (BCG, cholera, typhoid oral)
MechanismAntibacterial activity may inactivate live vaccine strains
EffectReduced vaccine efficacy
ManagementDelay live bacterial vaccines until antibiotic course is completed
Medscape
Minor
Multivitamins with iron (10 mg elemental iron)
MechanismSame chelation mechanism as therapeutic iron but lower iron content
EffectReduces cefdinir absorption by approximately 31%
ManagementSeparate by 2 hours if possible; iron-fortified infant formula (2.2 mg elemental iron/6 oz) does not require separation
FDA PI
Lab Test Interference
Cefdinir may cause false-positive urine glucose results with copper-reduction methods (Clinitest, Benedict’s solution) but not with enzymatic glucose oxidase tests. It may also produce a false-positive urine ketone reaction with nitroprusside-based tests. Cephalosporins as a class can occasionally induce a positive direct Coombs’ test without hemolysis.
Monitoring
-
Renal Function
Baseline
Routine Serum creatinine and estimated CrCl before initiating therapy, particularly in elderly patients and those with known renal disease. Dose adjustment required if CrCl <30 mL/min. -
Stool Character
Throughout therapy
Routine Counsel patients to report watery or bloody stools, which may indicate C. difficile colitis. Testing is indicated if diarrhea is severe or persistent. Red stools with concurrent iron use are harmless. -
Clinical Response
48–72 h after start
Routine Assess for clinical improvement (fever resolution, symptom reduction). If no improvement by 72 hours, re-evaluate diagnosis and consider culture and sensitivity testing. -
Allergic Reactions
First dose and ongoing
Trigger-based Observe for signs of hypersensitivity including rash, urticaria, angioedema, or respiratory distress, especially in patients with penicillin allergy (cross-reactivity may occur in up to 10%). -
Hepatic Function
If symptoms arise
Trigger-based Although cefdinir is not hepatically metabolized, rare postmarketing reports of acute hepatitis and hepatic failure exist. Check LFTs if jaundice, dark urine, or right upper quadrant pain develops. -
CBC
Prolonged courses (>14 days)
Trigger-based Rarely indicated for standard 5–10 day courses. For atypical prolonged use, monitor for leukopenia, eosinophilia, or thrombocytopenia as reported in clinical trials.
Contraindications & Cautions
Absolute Contraindications
- Known allergy to cefdinir or any cephalosporin antibiotic — history of anaphylaxis, angioedema, or severe hypersensitivity reaction to any cephalosporin
Relative Contraindications (Specialist Input Recommended)
- History of severe penicillin allergy (anaphylaxis, severe urticaria, bronchospasm) — cross-reactivity between penicillins and cephalosporins may occur in up to 10% of penicillin-allergic patients. For patients with a history of anaphylaxis to penicillin, an allergy evaluation or alternative non-beta-lactam antibiotic is recommended.
- Severe renal impairment (CrCl <30 mL/min) without dose adjustment — plasma AUC increases approximately 6-fold; must reduce dose to 300 mg once daily (adults) or 7 mg/kg once daily (pediatric)
Use with Caution
- History of gastrointestinal disease, especially colitis — higher risk of C. difficile-associated diarrhea
- Concurrent use of iron supplements or antacids — significant absorption impairment requiring temporal separation
- Patients with diabetes — oral suspension contains 2.86 g sucrose per 5 mL; may affect glycemic control
- Neonates and infants <6 months — safety and efficacy not established
FDA Class-Wide Regulatory Warning
Beta-Lactam Hypersensitivity
Serious and occasionally fatal hypersensitivity reactions have been reported in patients receiving beta-lactam antibiotics, including cephalosporins. Before initiating cefdinir therapy, a careful inquiry should be made regarding previous hypersensitivity reactions to cefdinir, cephalosporins, penicillins, or other drugs. Cross-hypersensitivity among beta-lactam antibiotics has been clearly documented. If an allergic reaction occurs, the drug should be discontinued and appropriate emergency treatment initiated.
Patient Counselling
Purpose of Therapy
Cefdinir is an antibiotic that works by stopping bacteria from building their protective cell walls, ultimately killing the infection. It treats bacterial infections only and will not help with viral illnesses like the common cold or flu. Taking the full course is critical to preventing the infection from returning and reducing the risk of antibiotic resistance.
How to Take
Cefdinir capsules or suspension may be taken with or without food. The suspension should be shaken well before each dose and measured with a calibrated oral syringe or dosing cup. Store reconstituted suspension at room temperature and discard any unused portion after 10 days. If taking the medication once daily, take it at the same time each day. If twice daily, try to space doses 12 hours apart.
Diarrhea
Tell patient
Loose stools are the most common side effect and usually resolve once the antibiotic course is completed. Stay well hydrated. Do not take anti-diarrheal medicines without consulting your prescriber first, as they can mask a more serious condition.
Call prescriber
If diarrhea becomes watery, bloody, or is accompanied by fever or severe abdominal cramps — this may indicate C. difficile infection and requires immediate evaluation. This can occur during or up to 2 months after finishing the antibiotic.
Red/Orange-Colored Stools
Tell patient
If you are also taking iron supplements, multivitamins containing iron, or if your child is on iron-fortified formula, stools may turn a reddish-orange color. This is a harmless chemical reaction between cefdinir and iron in the gut — it is not blood.
Call prescriber
If red stools are accompanied by abdominal pain, fever, or other concerning symptoms suggesting actual GI bleeding.
Separation from Iron & Antacids
Tell patient
Take cefdinir at least 2 hours before or after any antacids (aluminum or magnesium type) and iron supplements, including multivitamins with iron. These products significantly reduce the absorption and effectiveness of the antibiotic. Iron-fortified infant formula does not need to be separated.
Call prescriber
If you realize you have been taking these medications together throughout the course and your infection is not improving.
Allergic Reactions
Tell patient
As with all antibiotics, allergic reactions are possible. Mild rash may occur and should be reported but is not always an emergency. Inform your prescriber of any history of antibiotic allergies, especially to penicillin or other cephalosporins.
Call prescriber
Seek emergency medical attention immediately if you develop hives, difficulty breathing, swelling of the face, lips, tongue, or throat, or feel faint. These may indicate a serious allergic reaction.
Completing the Course
Tell patient
It is common to feel better within the first few days, but the full course must be completed as prescribed. Stopping early may allow the bacteria to survive and become resistant, making the infection harder to treat in the future.
Call prescriber
If symptoms are not improving within 48–72 hours of starting the medication or if they worsen at any point.
Sources
Regulatory (PI / SmPC)
- Cefdinir Capsules USP Prescribing Information. Lupin Pharmaceuticals, Inc. Revised August 2024. DailyMed Primary prescribing information for adult and adolescent capsule formulation; source for dosing, pharmacokinetics, adverse events, and contraindications.
- Cefdinir for Oral Suspension USP Prescribing Information. Lupin Pharmaceuticals, Inc. DailyMed Primary PI for pediatric suspension formulation; source for weight-based dosing and pediatric adverse event data.
- Omnicef (cefdinir) FDA Label, NDA 50-739 / 50-749. U.S. Food and Drug Administration. FDA.gov Original brand-name labeling; includes clinical trial efficacy data for pneumonia and pharyngitis.
Key Clinical Trials
- Tack KJ, Hedrick JA, Rothstein E, et al. A study of 5-day cefdinir treatment for streptococcal pharyngitis in children. Arch Pediatr Adolesc Med. 1997;151(1):45-49. DOI Demonstrated that a 5-day course of cefdinir BID was equivalent to 10 days of penicillin for pediatric pharyngitis.
- Tack KJ, Keyserling CH, McCarty J, Hedrick JA. Study of use of cefdinir versus cephalexin for treatment of skin infections in pediatric patients. Antimicrob Agents Chemother. 1997;41(4):739-742. DOI Established efficacy and safety of cefdinir BID for pediatric skin infections.
Guidelines
- Lieberthal AS, Carroll AE, Chonmaitree T, et al. The diagnosis and management of acute otitis media. Pediatrics. 2013;131(3):e964-e999. DOI AAP guideline recommending cefdinir as an alternative antibiotic for AOM in penicillin-allergic children.
- Chow AW, Benninger MS, Brook I, et al. IDSA clinical practice guideline for acute bacterial rhinosinusitis in children and adults. Clin Infect Dis. 2012;54(8):e72-e112. DOI IDSA guideline noting limitations of third-generation oral cephalosporins as empiric monotherapy for sinusitis due to variable pneumococcal resistance.
- Shulman ST, Bisno AL, Clegg HW, et al. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the IDSA. Clin Infect Dis. 2012;55(10):e86-e102. DOI Positions cefdinir as an acceptable alternative for GAS pharyngitis in penicillin-allergic patients without anaphylaxis history.
Mechanistic / Basic Science
- Niwa T, Shiraga T, Takagi A. Effect of cefdinir, a new oral cephalosporin, on the in vitro activity of cytochrome P450 in human liver microsomes. Biol Pharm Bull. 2002;25(12):1638-1642. DOI Confirmed that cefdinir does not undergo CYP-mediated metabolism, supporting its low drug interaction profile.
Pharmacokinetics / Special Populations
- Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron. 1976;16(1):31-41. DOI Foundational formula referenced in the cefdinir PI for estimating adult CrCl to guide renal dose adjustment.
- Schwartz GJ, Haycock GB, Edelmann CM, Spitzer A. A simple estimate of glomerular filtration rate in children derived from body length and plasma creatinine. Pediatrics. 1976;58(2):259-263. Schwartz equation for pediatric GFR estimation referenced in the PI for determining renal dose adjustments in children.
- Arguedas AG, Zaleska M, Stutman HR, et al. Comparative trial of cefdinir vs. amoxicillin/clavulanate potassium in the treatment of children with acute otitis media with effusion. Pediatr Infect Dis J. 1996;15(3):240-244. DOI Comparative trial supporting cefdinir efficacy in pediatric AOM, informing suspension dosing recommendations.
- Guay DR. Pharmacokinetics of cefdinir in patients with renal insufficiency. J Clin Pharmacol. 2000;40(9):1007-1012. DOI Characterized the dose-proportional increase in cefdinir exposure with declining renal function; basis for CrCl <30 dose reduction.