Dose of acyclovir for 15kg 4 year old fpr varicella
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acyclovir dose varicella chickenpox children mg/kg per dose AAP Red Book
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acyclovir varicella children treatment
Oral acyclovir dosing for varicella (chickenpox) - 15 kg, 4-year-old:
- Dose: 20 mg/kg/dose = 300 mg per dose
- Frequency: 4 times daily (every 6 hours while awake)
- Duration: 5 days
- Maximum: 800 mg/dose (not reached here since 300 mg < 800 mg cap)
So: acyclovir 300 mg PO four times a day for 5 days, started ideally within 24 hours of rash onset (efficacy drops sharply after that window).
This is consistent across the AAP Red Book, Virginia pediatric antiviral dosing guide, and Fitzpatrick's/Dermatology 2-Volume Set (which notes oral acyclovir is FDA-approved for varicella in children 2-17 years) - Dermatology 2-Volume Set, 5e.
Important caveats:
- Routine treatment is usually not recommended for healthy immunocompetent children with uncomplicated varicella - most guidelines reserve antiviral therapy for those with risk factors: age >12 years, chronic cutaneous or pulmonary disease, long-term salicylate or corticosteroid therapy, secondary household transmission (which tends to be more severe), or immunocompromise. A well 4-year-old with routine chickenpox typically just gets supportive care (antihistamines for itch, nail trimming, antipyretics - avoid aspirin because of Reye syndrome risk).
- If immunocompromised or with severe/complicated disease (pneumonia, encephalitis, disseminated disease), IV acyclovir is used instead: 10 mg/kg/dose (or 500 mg/m2) IV every 8 hours for at least 7-10 days, per pediatric HIV/OI guidelines and Goldman-Cecil Medicine.
- Confirm renal function is normal and ensure adequate hydration, since acyclovir can crystallize in renal tubules at high doses.
A quick check of recent systematic reviews (PMIDs 38658176, 41175678, 37473793) did not surface anything that changes this standard 20 mg/kg/dose QID x5 days recommendation - those papers concerned CMV prophylaxis and post-vaccination neurological reactivation, not core varicella dosing.
If you can tell me whether this child is otherwise healthy or has a risk factor (immunosuppression, chronic lung/skin disease, steroid use), I can confirm whether treatment is actually indicated versus supportive care alone.
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