Pediatric Drug Dosing Reference

PICU DRUG INFORMATION


Acyclovir

Antiviral


Herpes simplex encephalitis
IV:
3 months - 12 years: 10 - 15 mg/kg (maximum: 1 g/dose) Q8H
13 years or older: 10 mg/kg (maximum: 1 g/dose) Q8H

Neonatal HSV
IV:
Treatment: 20 mg/kg Q8H for at least 14 days for skin/ocular/mouth disease (mucous membrane involvement) and a minimum of 21 days for CNS disease.

PO:
Suppressive therapy following Neonatal HSV: 300 mg/m2 TID for 6 months
Suppressive therapy should be offered to infants with CNS disease. Data is less convincing for skins, eyes and mucous membrane or disseminated disease, but can be offered.

Other herpes simplex infections
IV:
5 - 10 mg/kg (maximum: 1 g/dose) Q8H

PO:
20 mg/kg TID-QID

Varicella (severe) or in immunocompromised
IV:
10 mg/kg (maximum: 1 g/dose) Q8H
Therapy not always indicated in immunocompetent host.

PO:
20 mg/kg (maximum: 800 mg/dose) QID
Therapy not always indicated in immunocompetent host.

Base dose on ideal body weight. Ensure adequate hydration and urine output (especially on high dose IV therapy). Monitor renal function and extend dosing interval to q12h or q24h in renal impairment

Availability: Tablets: 200, 400 mg.
See valACYclovir if liquid required as acyclovir suspension requires compounding, has poor oral bioavalability, and needs for frequent dosing.

Pharmacology: Antiviral agent effective against herpes simplex 1 and herpes simplex 2, and varicella. Synthetic nucleoside analogue that inhibits viral DNA synthesis. Largely excreted unchanged by kidney therefore needs dose adjustments in renal failure

Updated: 06/01/2026

Contact Information: This resource is maintained by Mark Duffett (duffett@hhsc.ca), Jon Wong (wongjon@hhsc.ca), and Sally Thai (thais@hhsc.ca).
Disclaimer: This document has been created specifically for Hamilton Health Sciences (HHS) to use for its own patients and the information contained herein may not be applicable or relevant to other health care organizations. This document is for informational purposes only and is not intended to be a substitute for medical or clinical advice from a qualified health care professional. HHS makes no representations or warranties as to the accuracy of the information. This material is current only to the date listed. This material is the intellectual property of HHS and may not be shared, duplicated, or distributed further without the consent of HHS. HHS assumes no liability for the use of this information by the recipient.