Cefdinir is generally well-tolerated in children, with most side effects being mild and self-limited. Gastrointestinal symptoms are most common, affecting approximately 8-15% of pediatric patients, with diarrhea being more frequent in children under 2 years. The distinctive red stool discoloration from iron interaction is benign but may alarm parents. Serious adverse events like pseudomembranous colitis are rare but require immediate attention.
The most common side effect, affecting 8% of pediatric patients overall, with higher rates (15%) in adults and up to 17% in children ≤2 years. Usually mild and self-limited, resolving without intervention. Management includes maintaining hydration and considering probiotics (Lactobacillus rhamnosus GG or Saccharomyces boulardii at 5-40 billion CFU/day) if approved by provider. Monitoring: Persistent or severe diarrhea may indicate antibiotic-associated colitis (including C. difficile infection) and should be evaluated promptly, especially if bloody or with fever.
A distinctive but benign effect occurring when cefdinir interacts with iron in the GI tract, leading to reddish or rust-colored stools within 24-48 hours. This alarming appearance is not harmful and does not indicate bleeding or infection. Common in children taking iron-fortified formulas or supplements. Management: Reassure caregivers this is normal; separate iron supplements by 2 hours from cefdinir doses. Monitoring: Distinguish from actual blood in stool by noting the characteristic rust color and timing with iron intake.
Non-specific rash, usually maculopapular and non-itchy, occurring more frequently in children under 2 years than older children and adults in clinical trials. While not always indicating true allergy, any rash warrants provider evaluation. Management: Continue medication if mild and child is otherwise well, but provider should assess. Use antihistamines or topical steroids per provider recommendation. Monitoring: Stop drug and seek immediate care for urticaria (hives), facial swelling, or signs of serious allergic reactions like difficulty breathing.
Cefdinir absorption is significantly reduced by antacids containing aluminum or magnesium, and iron supplements, potentially leading to treatment failure. Probenecid can increase cefdinir levels and toxicity risk. Management: Separate antacids and iron products by 2 hours before or after cefdinir. Iron-fortified infant formulas are acceptable. Avoid probenecid during treatment. Monitoring: Watch for reduced effectiveness if interaction occurs, and ensure proper spacing of medications.
Rare but important complications include Stevens-Johnson syndrome, toxic epidermal necrolysis, and C. difficile-associated diarrhea (CDAD). Some parents report behavioral changes in toddlers, though specific incidence data is limited. Management: Discontinue immediately for severe skin reactions or signs of CDAD. Seek emergency care for widespread rash with fever or severe, persistent diarrhea with cramping. Monitoring: Watch for severe skin reactions, bloody diarrhea, fever, or unusual behavioral changes during treatment.
Cefdinir adverse effects mirror those of other cephalosporins, with diarrhea (8-17% depending on age), skin rash (more common in children <2 years), and nausea being most frequent. Distinctive red stool discoloration occurs with iron co-administration. Serious events include pseudomembranous colitis, severe skin reactions (Stevens-Johnson syndrome), and potential nephrotoxicity when combined with aminoglycosides.
3 documented effects
1-3 days after discontinuation
Maintain hydration; consider probiotics (L. rhamnosus GG or S. boulardii 5-40 billion CFU/day); avoid anti-diarrheal medications
Report if severe, bloody, persistent >3 days, or associated with fever/cramping
Resolves after iron separation or drug discontinuation
Reassure caregivers; separate iron supplements by 2 hours; iron-fortified formulas are acceptable
Distinguish from actual blood in stool; characteristic rust color with iron timing
Self-limited; resolves between doses
Give with food if stomach upset occurs; ensure adequate hydration
Report persistent vomiting preventing oral intake or signs of dehydration
2 documented effects
Up to 1 week after discontinuation
Continue if mild and child well; antihistamines or topical steroids per provider guidance
Seek immediate care for hives, facial swelling, or breathing difficulty
Can be prolonged; requires intensive care
Discontinue immediately; emergency medical care; supportive treatment
Watch for widespread rash with fever, blistering, or mucosal involvement
1 documented effect
Usually resolves after discontinuation
Monitor closely; consider alternative antibiotic if severe; supportive care
Report unusual hyperactivity, irritability, sleep disturbances, or mood changes
1 documented effect
Variable; may require dose adjustment or discontinuation
Monitor renal function; adjust doses based on creatinine clearance; avoid combination when possible
Regular serum creatinine and BUN monitoring; watch for decreased urine output
Age under 2 years (higher risk of diarrhea and rash)
Concurrent iron supplementation (red stool discoloration)
History of cephalosporin or penicillin allergy
Concurrent aminoglycoside therapy (nephrotoxicity risk)
Previous C. difficile infection or recent antibiotic use
Use probiotics (L. rhamnosus GG or S. boulardii 5-40 billion CFU/day) to prevent antibiotic-associated diarrhea (NNT=6-9); separate iron supplements and antacids by 2 hours; maintain hydration; complete full course even if symptoms improve; take with food if GI upset occurs
📞 Call your pediatrician immediately if you notice any of these symptoms:
Severe, bloody, or persistent diarrhea with fever or cramping
Widespread rash with fever, blistering, or mouth/eye involvement
Signs of allergic reaction (hives, facial swelling, difficulty breathing)
Severe dehydration from vomiting or diarrhea
Unusual behavioral changes or severe irritability in toddlers
Signs of kidney problems (decreased urination, swelling, fatigue)
| Effect | Cefdinir | Amoxicillin |
|---|---|---|
| Diarrhea | 8-17% (age-dependent) | ≈10% |
| Red stool discoloration | Common with iron | Does not occur |
| Drug interactions | Significant with iron/antacids | Minimal |
Reduced cefdinir absorption; separate by 2 hours before or after
Reduced absorption and red stool discoloration; separate by 2 hours
Increased cefdinir levels and toxicity risk; monitor closely
Increased nephrotoxicity risk; monitor renal function closely
Reduced vaccine effectiveness; wait until antibiotic course complete
Cefdinir is safe for babies over 6 months old. If your baby takes iron-fortified formula, you may notice rust-colored stools - this is completely normal and harmless. Watch for unusual fussiness, decreased feeding, or rash.
Your toddler's medicine might make their poop look reddish like rust if they take vitamins with iron. This isn't scary - it's just the medicine mixing with iron. Some toddlers may be a bit fussier or have looser stools while taking this medicine.
Cefdinir is an antibiotic that helps fight infections. If you take vitamins with iron, your poop might look red or rust-colored - this is normal and not dangerous. Tell your parents if you feel sick, get a rash, or have bad stomach aches.
Cefdinir may cause red-colored stools if taken with iron supplements or multivitamins containing iron. This is a harmless interaction, not bleeding. Complete the full course even if you feel better, and report severe diarrhea, rash, or allergic reactions.
A: Red stools from cefdinir + iron interaction are completely harmless. This is not blood and doesn't require stopping the medication. Continue the full antibiotic course as prescribed.
When to validate: Contact us if stools are truly bloody (bright red with visible blood), black and tarry, or if your child has severe abdominal pain or signs of illness.
A: Yes, cefdinir is safe for most children with penicillin allergies (less than 1% cross-reaction risk). The American Academy of Pediatrics recommends it for penicillin-allergic children.
When to validate: Do not use if the penicillin reaction was severe (breathing problems, facial swelling, emergency treatment). Contact us immediately if any new allergic symptoms develop.
A: You may separate iron supplements by 2 hours to reduce red stool discoloration and slightly improve absorption, but it's not medically necessary. Continue iron-fortified formula normally.
When to validate: Contact us if you have concerns about medication timing or if your child isn't improving as expected.
A: Some toddlers experience mild behavioral changes (irritability, sleep disruption) while on antibiotics. This is usually temporary and resolves after completing treatment.
When to validate: Contact us if behavioral changes are severe, persistent beyond treatment, or if you notice other concerning symptoms.
Evidence-based clinical assessment framework for cefdinir adverse effects with specific focus on unique characteristics
Parent and clinician concerns about Cefdinir