What cefdinir dose and treatment duration should I give a 21.36 kg child (≥2 years) with mild‑moderate infection, and what alternative is recommended if the child has a severe IgE‑mediated allergy to penicillins and cephalosporins?

Cefdinir Dosing for a 21.36 kg Child with Mild-Moderate Infection

For a 21.36 kg child (≥2 years) with mild-moderate infection, prescribe cefdinir 150 mg every 12 hours (7 mg/kg/dose) for 5-7 days, and if the child has a severe IgE-mediated allergy to both penicillins and cephalosporins, use azithromycin 10 mg/kg on day 1 (max 500 mg) followed by 5 mg/kg once daily on days 2-5 (max 250 mg/day). 1, 2

Standard Cefdinir Dosing Algorithm

Twice-daily regimen (preferred):

• The American Academy of Pediatrics recommends 7 mg/kg every 12 hours for pediatric patients aged 6 months through 12 years 2
• For this 21.36 kg child: 7 mg/kg × 21.36 kg = 149.5 mg (round to 150 mg) every 12 hours 2
• Total daily dose: 300 mg/day (14 mg/kg/day) 2

Once-daily alternative:

• The Infectious Diseases Society of America recommends 14 mg/kg every 24 hours for certain indications including acute otitis media, sinusitis, and pharyngitis/tonsillitis 2
• For this child: 14 mg/kg × 21.36 kg = 299 mg (round to 300 mg) once daily 2

Treatment Duration

• Prescribe 5-7 days of therapy for most mild-moderate respiratory tract infections and skin infections 1, 3, 4
• Reassess if symptoms persist beyond 48-72 hours 1

Clinical Context and Positioning

Cefdinir is an alternative agent, not first-line therapy:

• The Infectious Diseases Society of America positions cefdinir alongside cefixime, cefpodoxime, and ceftibuten as alternatives when amoxicillin-clavulanate cannot be used 2
• Cefdinir has a specific role in treating β-lactamase-producing Haemophilus influenzae in community-acquired pneumonia 2
• High-dose amoxicillin (90 mg/kg/day) remains superior for resistant pneumococcal infections 2

Cefdinir provides good coverage for:

• Haemophilus influenzae (including β-lactamase-producing strains) 3, 4
• Moraxella catarrhalis (including β-lactamase-producing strains) 3, 4
• Penicillin-susceptible Streptococcus pneumoniae 4
• Staphylococcus aureus and Streptococcus pyogenes 5

Management of Severe IgE-Mediated β-Lactam Allergy

If the child has a severe IgE-mediated (Type 1) allergy to BOTH penicillins AND cephalosporins:

First-line alternative: Azithromycin

• The Infectious Diseases Society of America recommends azithromycin for β-lactam allergy (Type 1 hypersensitivity) 1
• Dosing: 10 mg/kg on day 1 (max 500 mg), then 5 mg/kg once daily on days 2-5 (max 250 mg/day) 1
• For this 21.36 kg child: 214 mg (round to 200-250 mg) on day 1, then 107 mg (round to 100-125 mg) on days 2-5 1

Second-line alternative: Clarithromycin

• The Infectious Diseases Society of America recommends clarithromycin 15 mg/kg/day in 2 doses as an alternative 1
• For this child: 15 mg/kg × 21.36 kg = 320 mg/day divided into 160 mg every 12 hours 1

For adolescents with skeletal maturity (generally ≥16 years) with severe β-lactam allergy:

• Levofloxacin 8-10 mg/kg once daily (max 750 mg) is acceptable 1
• This option is NOT appropriate for a younger child weighing 21.36 kg 1

Important Caveat About Non-Type 1 Penicillin Allergy

If the child has a non-anaphylactic (non-Type 1) penicillin allergy, cefdinir IS appropriate:

• The American Academy of Pediatrics suggests considering oral cephalosporins such as cefdinir for non-Type 1 penicillin allergy 1
• Cross-reactivity between penicillins and third-generation cephalosporins like cefdinir is extremely low (< 1%) for non-IgE-mediated reactions 1
• Only avoid cefdinir if the child has documented IgE-mediated allergy to cephalosporins specifically 1

Common Pitfalls to Avoid

Do not use cefdinir for penicillin-resistant Streptococcus pneumoniae:

• Research demonstrates that even a higher dose of 25 mg/kg daily would be ineffective for penicillin-nonsusceptible S. pneumoniae 6
• High-dose amoxicillin (90 mg/kg/day) remains the preferred agent for resistant pneumococcal infections 1, 2

Do not confuse Type 1 (IgE-mediated) with non-Type 1 penicillin allergy:

• Cefdinir can be used safely in non-Type 1 penicillin allergy 1
• Only switch to azithromycin or clarithromycin if the child has documented anaphylaxis, urticaria, or other IgE-mediated reactions to β-lactams 1

Monitor for diarrhea:

• Diarrhea occurred in 20% of subjects receiving higher doses of cefdinir in pharmacokinetic studies 6
• Diarrhea and soft stools are the most common adverse events but are usually mild 5, 7