Acyclovir Dosing for 9-Year-Old Female with Herpes Simplex Dermatitis
For a 9-year-old female with herpes simplex dermatitis (mucocutaneous HSV infection), the recommended dose is acyclovir 20 mg/kg orally three times daily (maximum 400 mg/dose) for 7-14 days. 1
Oral Therapy for Mucocutaneous HSV in Children
The standard pediatric dosing for mucocutaneous herpes simplex infections in immunocompetent children is:
- Acyclovir 20 mg/kg orally three times daily (maximum 400 mg/dose) for 7-14 days 2, 1
- For a typical 9-year-old weighing approximately 30 kg, this translates to approximately 600 mg three times daily, but should not exceed 400 mg per dose 1
This dosing is specifically recommended by the CDC and American Academy of Pediatrics for children with HSV infections including dermatitis/mucocutaneous disease 2, 1.
When to Consider Intravenous Therapy
Escalate to IV acyclovir if the patient has:
- Severe disease requiring hospitalization 2
- Immunocompromised status 2
- Disseminated infection or CNS involvement 2
For severe mucocutaneous HSV requiring hospitalization, the dose is acyclovir 5-10 mg/kg IV every 8 hours for 7-14 days 2.
Treatment Duration and Monitoring
- Continue treatment for 7-14 days depending on clinical response 2, 3
- For immunocompetent children with localized disease, 7-10 days is typically sufficient 2, 3
- Longer courses (up to 14 days) may be needed for extensive involvement or slow healing 2, 3
Important Clinical Considerations
Common pitfalls to avoid:
- Do not use topical acyclovir as primary therapy - it provides minimal benefit for systemic symptoms and is significantly less effective than oral formulations 4, 5
- Ensure adequate hydration - acyclovir is primarily renally excreted and requires dose adjustment in renal insufficiency 2, 6
- Monitor for neutropenia - this is the most common toxicity in children receiving acyclovir, though usually self-limited 2
For immunocompromised patients (HIV, transplant, chemotherapy):
- Higher doses may be required: acyclovir 400 mg orally 3-5 times daily 2, 1
- Consider longer treatment duration (14 days or until complete resolution) 2
- Be vigilant for acyclovir resistance if lesions persist despite therapy 2
Alternative Considerations
If the patient is postpubertal and can swallow adult-sized tablets, valacyclovir or famciclovir may offer more convenient dosing with comparable efficacy, though pediatric dosing data are limited 2, 3. However, standard acyclovir remains the first-line agent with the most established safety profile in children 2, 1.