Antibiotic and Corticosteroid Dosing for Beta-Lactam Allergic One-Year-Old
For a one-year-old with hives after amoxicillin and cefdinir, azithromycin should be dosed at 10 mg/kg on day 1, followed by 5 mg/kg/day once daily on days 2-5 for the ear infection, and prednisone at 1-2 mg/kg/day divided into 1-2 doses for 3-5 days for the allergic reaction. 1
Azithromycin Dosing for Ear Infection
Azithromycin is the appropriate alternative antibiotic for this child who has developed hives (indicating possible Type I hypersensitivity) to two beta-lactam antibiotics (amoxicillin and cefdinir). 1, 2
Standard pediatric dosing: 10 mg/kg on day 1 (maximum 500 mg), followed by 5 mg/kg once daily on days 2-5 (maximum 250 mg per day). 1
This child has demonstrated reactions to both a penicillin (amoxicillin) and a cephalosporin (cefdinir), making macrolides like azithromycin the safest choice, as they have no cross-reactivity with beta-lactams. 2
The American Academy of Otolaryngology-Head and Neck Surgery specifically recommends macrolides (azithromycin, clarithromycin, or erythromycin) for children with Type I hypersensitivity reactions to beta-lactams. 1
Important Caveats About Macrolide Efficacy
Be aware that macrolides have limited effectiveness against major pathogens of acute otitis media, with bacterial failure rates of 20-25%. 1, 3
If the child fails to respond after 72 hours of azithromycin therapy, reevaluation is necessary, potentially including tympanocentesis for culture or consideration of parenteral antibiotics. 1
Azithromycin provides better coverage than clarithromycin or erythromycin and has superior compliance due to once-daily dosing and shorter treatment duration. 4
Prednisone Dosing for Hives
Prednisone dosing for acute urticaria/hives: 1-2 mg/kg/day orally, divided into 1-2 doses, for 3-5 days. This is standard pediatric practice for acute allergic reactions with cutaneous manifestations.
The typical approach is to start at 1 mg/kg/day for mild-to-moderate hives, escalating to 2 mg/kg/day (maximum 60 mg/day) if symptoms are severe or not responding.
A short course (3-5 days) is generally sufficient for drug-induced urticaria and does not require tapering in otherwise healthy children.
Antihistamines (such as cetirizine 0.25 mg/kg/dose once or twice daily, or diphenhydramine 1 mg/kg/dose every 6 hours) should be used concurrently as first-line therapy, with corticosteroids reserved for moderate-to-severe cases or those not responding to antihistamines alone.
Critical Clinical Considerations
Distinguishing True Allergy from Viral Exanthem
Amoxicillin-associated rashes in children are common, with >90% tolerating amoxicillin on re-exposure. 5
The timing of rash onset is crucial: rashes appearing on days 7-10 of treatment are more likely viral exanthems or delayed hypersensitivity reactions rather than IgE-mediated allergy. 5
However, this child developed hives with two different beta-lactam antibiotics, which increases the likelihood of true beta-lactam allergy and warrants avoidance of this entire class. 1
When to Refer to Allergy
This child should be referred to pediatric allergy/immunology after acute treatment for formal evaluation, including possible skin testing and graded challenge, to definitively determine if true beta-lactam allergy exists. 5
Formal allergy evaluation is particularly important given that this child has now been labeled allergic to two major antibiotic classes, which will significantly limit future treatment options.
Monitoring and Follow-up
Reassess at 48-72 hours to ensure clinical improvement of both the ear infection and the allergic reaction. 1
If hives worsen or systemic symptoms develop (angioedema, respiratory symptoms, gastrointestinal symptoms), immediate reevaluation is necessary as this may indicate progression to anaphylaxis. 5
Parents should be counseled that "worrisome" systemic symptoms (fever, angioedema, gastrointestinal symptoms) occur in a significant proportion of children with drug reactions but do not necessarily indicate anaphylaxis. 5