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Ampicillin is an aminopenicillin antibiotic. Outpatient oral use in children is selective; dosing is provided for pediatrics when clinically appropriate.
Time-dependent activity means maintaining q4–6h dosing intervals is crucial
For neonates, dosing depends on gestational and postnatal age—use institutional guidelines
Frequent partner with gentamicin for synergy against Listeria and Enterococcus
Avoid in suspected Epstein–Barr virus (EBV) pharyngitis due to high rash incidence
Ampicillin remains a cornerstone for neonatal sepsis, meningitis, and select culture-directed infections caused by susceptible organisms (Listeria, Enterococcus, non–beta-lactamase Gram-negatives).
Use ampicillin with gentamicin for empiric neonatal coverage, continue for confirmed Listeria/Enterococcus, and employ oral formulations selectively for step-down therapy when susceptibility is proven.
| Condition | Age Range | First Line? | Notes |
|---|---|---|---|
| Early-onset neonatal sepsis or meningitis (with gentamicin) | Neonates | Yes | Covers group B Streptococcus, Listeria, and Enterococcus; dosing interval depends on gestational and postnatal age. |
| Listeria monocytogenes or Enterococcus infections | Infants and children | Yes | Combine with gentamicin for synergy in meningitis, bacteremia, or osteoarticular disease when isolates are susceptible. |
| Susceptible gram-negative urinary or gastrointestinal infections | Children and adolescents | No | Use when culture confirms ampicillin-susceptible enteric organisms and resistance rates are low. |
| Intrapartum group B Streptococcus prophylaxis when penicillin G unavailable | Peripartum patients | Yes | Administer 2 g IV loading dose followed by 1 g IV every 4 hours until delivery. |
| Culture-directed shigellosis step-down therapy | Children | No | Consider oral ampicillin when isolates are susceptible and the child is clinically improving. |
FDA-approved primary uses with Level A evidence
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Quick selection guides and diagnostic pearls
When to consider other medications
How to explain treatment to families
Ampicillin is usually well tolerated, but monitor for diarrhea, hypersensitivity, hematologic changes, and EBV-associated rash.
Counsel families about the difference between benign maculopapular rashes and IgE-mediated allergies, and advise prompt evaluation for severe diarrhea or hepatic symptoms during prolonged therapy.
Diarrhea / loose stools
Common • mild
Clostridioides difficile–associated diarrhea
Rare • severe
Maculopapular rash (non-IgE, especially with EBV)
Common in infectious mononucleosis • mild
Immediate hypersensitivity (urticaria, angioedema, anaphylaxis)
Rare • severe
Neutropenia / thrombocytopenia / anemia
Rare • moderate
Hepatic dysfunction / cholestatic jaundice
Rare • moderate
Organized by affected organ systems
How to discuss side effects with families
Management protocols and monitoring
Common concerns and practical guidance
Ampicillin is used both orally and intravenously; dosing varies by age, weight, renal maturity, and infection severity.
Different formulations and concentrations
Safe preparation and measuring techniques
Tailored approaches for different ages
Solutions for common challenges
Storage guidelines and safety tips
Expert pearls and evidence-based tips
Ampicillin is an aminopenicillin that inhibits bacterial cell wall synthesis and achieves synergy with aminoglycosides against select pathogens.
Simple explanations and helpful analogies
Receptors, enzymes, and cellular targets
Absorption, metabolism, and elimination
Age-related differences and special populations
Clinical pearls to optimize ampicillin use across neonatal and pediatric settings.
Core insights every provider should know
Recent updates that change how we practice
Organized by dosing, administration, and safety
How to explain treatments to families
Real-world cases with evidence-based approaches
Key numbers, algorithms, and decision tools
Understanding your child's medication is important. We've created comprehensive guides to help you safely administer Ampicillin and monitor your child's response to treatment.
The combination covers the most common causes of early-onset sepsis (Group B strep, Listeria, Enterococcus, Gram-negative rods) by providing complementary mechanisms.
Not always. Ampicillin causes a benign rash in many children with Epstein–Barr virus. Stop the medicine and call your clinician to determine if it represents allergy or a viral rash.
Give doses every 6 hours on an empty stomach (for example 6 am, noon, 6 pm, midnight). Set alarms or discuss alternatives if this schedule is unrealistic.