From the Guidelines

Acyclovir is the treatment of choice for Herpes Simplex Labialis in children.

The recommended dose of acyclovir for children is 20 mg/kg body weight (max 400 mg/dose) per dose orally 2 times daily 1.
For children old enough to receive adult dosing, valacyclovir 500 mg orally 2 times daily or famciclovir 500 mg orally 2 times daily can be used as alternative treatments 1.

Acyclovir has been shown to be effective in reducing the duration of symptoms and accelerating healing of lesions associated with herpes labialis 1.
The aim of antiviral therapy is to block viral replication, enabling shortening of the duration of symptoms and acceleration of healing of the lesions associated with herpes labialis 1.
Topical antiviral medications are not effective prophylactically, and their use is limited to reducing the duration of symptoms 1.

The treatment of herpes labialis in children should be based on the severity and frequency of recurrences, as well as the child's overall health status 1.
Antiviral therapy should be started early in the course of the disease to maximize its effectiveness 1.

From the Research

The treatment for Herpes Simplex Labialis in children can be considered according to severity and time of acquisition 2.
For children less than 12 years of age, oral acyclovir is administered at a dosage of 20 mg/kg every eight hours 2.
Although no controlled studies have been performed with valaciclovir or famciclovir in children, the pharmacokinetics of these medications would suggest superiority over acyclovir 2.
Dosage recommendations have not been established for young children, and for postpubertal children, dosage should mirror that of adults 2.
Valaciclovir is administered at 500 mg twice daily, and famciclovir is administered at 125 mg three times daily for postpubertal children 2.

Antiviral therapy can be used to block viral replication, which shortens the duration of symptoms, facilitates resolution of lesions, and lessens the risk of spreading the virus 3.
Oral antiviral agents, such as acyclovir, valacyclovir, and famciclovir, are superior to topical antiviral therapy for episodic treatment of herpes labialis 4.
Topical antiviral agents, such as 5% acyclovir cream/ointment, 1% penciclovir cream, and 50 mg Buccal Adhesive Tablet, can also be used for episodic treatment of herpes labialis 4.
Single-dose famciclovir has been shown to be an effective and convenient therapy for recurrent herpes labialis 5.

Physician judgment is required for the management of recurrent herpes labialis in children, as no controlled studies have been performed in this population 2.
The pharmacist may advise the patient to prevent recurrence and the contamination of other people, and may recommend symptomatic treatment or antiviral therapy 6.