What is the dose of acyclovir (antiviral medication) for a child with eczema herpeticum?

Acyclovir Dosing for Eczema Herpeticum in Children

For children with eczema herpeticum, administer oral acyclovir 20 mg/kg per dose (maximum 400 mg/dose) three times daily for 5-10 days for mild to moderate disease, or intravenous acyclovir 5-10 mg/kg per dose three times daily for severe disease requiring hospitalization. 1, 2

Mild to Moderate Disease (Outpatient Management)

• Oral acyclovir 20 mg/kg per dose (maximum 400 mg/dose) three times daily is the standard treatment for children who can be managed as outpatients. 1, 2
• Continue therapy for 5-10 days until lesions completely heal, not just until improvement begins. 1
• Initiate treatment within the first 3 days of symptom onset for maximum efficacy, as peak viral replication occurs in the first 24 hours after lesion onset. 1
• Monitor for clinical improvement within 48-72 hours of starting therapy. 1, 2

Severe Disease (Inpatient Management)

• For severe eczema herpeticum requiring hospitalization, start with intravenous acyclovir 5-10 mg/kg per dose three times daily. 1, 2
• After lesions begin to regress, transition to oral acyclovir at the same weight-based dosing (20 mg/kg per dose three times daily) to complete the treatment course. 1, 2
• Continue treatment until complete healing occurs, which may extend beyond the initial 5-10 day period. 1

Special Population: Neonates

• For neonates with eczema herpeticum, use higher doses of intravenous acyclovir 20 mg/kg IV every 8 hours, as recommended for neonatal HSV infections. 3, 2
• Neonatal skin, eye, or mouth disease requires acyclovir 20 mg/kg IV three times daily for 14 days. 3

Critical Safety Monitoring

• Ensure adequate hydration throughout treatment to prevent acyclovir crystalluria and renal toxicity. 1, 2
• Monitor renal function, particularly with intravenous administration. 1, 2
• Watch for neutropenia, which occurs in approximately 21-46% of infants on prolonged therapy, though it is typically self-limited. 1
• Dose adjustment is required if renal insufficiency develops. 1

Treatment Failure and Resistance

• If the child fails to respond after 5-7 days of appropriate acyclovir therapy, consider acyclovir-resistant HSV. 1
• Switch to intravenous foscarnet 40 mg/kg per dose three times daily for acyclovir-resistant HSV infection. 1, 2

Common Pitfalls to Avoid

• Do not use topical antivirals alone, as they cannot reach the site of viral reactivation or impact the host immune response. 1
• Do not stop treatment early when symptoms improve; continue until complete healing occurs to prevent recurrence. 1
• Do not delay treatment while awaiting laboratory confirmation—eczema herpeticum is a clinical diagnosis and requires immediate empiric therapy. 2, 4
• Be vigilant for signs of dissemination or bacterial superinfection (particularly Pseudomonas or Staphylococcus), which can complicate the clinical course and may be life-threatening. 4