What is the recommended dosing for antiviral medications, such as acyclovir (antiviral medication), for pediatric patients with recurrent herpes simplex labialis (cold sores)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: June 29, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

From the Guidelines

For pediatric patients with recurrent herpes simplex labialis (cold sores), the recommended dosing for acyclovir is 20 mg/kg body weight (max 400 mg/dose) per dose orally 3 times daily for 5--14 days. This dosing is based on the guidelines from the CDC, NIH, and other reputable organizations, as outlined in the study published in 2009 1. The treatment should be initiated as soon as possible, ideally during the prodromal phase when symptoms first appear.

  • Key considerations for treatment include:
    • Weight-based dosing for children under 45 kg
    • Maximum dose of 400 mg per dose
    • Treatment duration of 5--14 days
    • Oral administration, 3 times daily It's essential to note that these guidelines are specific to children under 45 kg, and dosing for adults and adolescents may differ, as outlined in the same study 1. By following these guidelines, pediatric patients with recurrent cold sores can receive effective treatment to reduce the severity and duration of symptoms, ultimately improving their quality of life.

From the Research

Pediatric Dosing for Recurrent Cold Sore Treatment

The recommended dosing for antiviral medications, such as acyclovir, for pediatric patients with recurrent herpes simplex labialis (cold sores) is as follows:

  • For children less than 12 years of age, oral acyclovir is administered at a dosage of 20 mg/kg every eight hours 2
  • For postpubertal children, dosage should mirror that of adults, with valaciclovir administered at 500 mg twice daily and famciclovir administered at 125 mg three times daily 2
  • Some studies suggest that acyclovir can be administered orally at a dose adjusted by age: 20 mg/kg for 5 to 7 years of age, 15 mg/kg for 7 to 12 years, and 10 mg/kg for 12 to 16 years 3

Considerations for Treatment

  • The treatment of recurrent herpes labialis in children requires physician judgment, as no controlled studies have been performed in this population 2
  • Antiviral medications such as acyclovir, valaciclovir, and famciclovir have been used to treat recurrent herpes labialis, although the majority of data on their use has been generated in adults 2, 4
  • The management of acyclovir-resistant herpes simplex virus may require alternative treatment regimens, including the use of intravenous foscarnet or cidofovir 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Herpes Simplex Virus in Children.

Current treatment options in neurology, 2002

Research

Valacyclovir. New indication: for genital herpes, simpler administration.

Canadian family physician Medecin de famille canadien, 1999

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.