Aciclovir Dosage for HSV and VZV Infections
Herpes Simplex Virus (HSV) - Oral Therapy
- The Centers for Disease Control and Prevention (CDC) recommends Aciclovir 400 mg orally 3 times a day for 5 days, or 800 mg orally 2 times a day for 5 days, for recurrent genital or oral HSV episodes 1, 2
- For patients with frequent recurrences (≥6 episodes per year), the CDC recommends Aciclovir 400 mg orally 2 times a day for suppressive therapy, which reduces the recurrence frequency by ≥75% 1, 2, 3
- The American Academy of Pediatrics recommends Aciclovir 20 mg/kg body weight (max 400 mg/dose) orally 3 times a day for 5-14 days for children <45 kg with first episode genital herpes 4
Severe HSV Disease - Intravenous Therapy
- For severe disease or complications requiring hospitalization, the CDC recommends Aciclovir 5-10 mg/kg body weight intravenously every 8 hours for 5-7 days or until clinical improvement 1, 2, 5
- For central nervous system (CNS) disease in children, the American Academy of Pediatrics recommends Aciclovir 10 mg/kg body weight intravenously 3 times a day for 21 days 4
Varicella-Zoster Virus (VZV) - Herpes Zoster
- For severe disease or complications, the CDC recommends Aciclovir 5-10 mg/kg body weight intravenously every 8 hours for 5-7 days or until clinical improvement 5
Aciclovir-Resistant HSV Infection
- For Aciclovir-resistant HSV infection, the CDC recommends Foscarnet 40 mg/kg intravenously 3 times a day or 60 mg/kg intravenously 2 times a day as the therapy of choice 4
Important Warnings
- For immunosuppressed patients, higher doses may be required: Aciclovir 400 mg orally 3-5 times a day for suppression 3
- High-dose Valaciclovir (8 g/day) should be avoided in immunosuppressed patients due to the risk of hemolytic-uremic syndrome or thrombotic thrombocytopenic purpura 3
Acyclovir Treatment for Mucocutaneous Herpes Simplex Infections in Children
Oral Therapy for Mucocutaneous HSV in Children
- The Centers for Disease Control and Prevention (CDC) and American Academy of Pediatrics recommend acyclovir 20 mg/kg orally three times daily (maximum 400 mg/dose) for 7-14 days for immunocompetent children with mucocutaneous herpes simplex infections, including dermatitis/mucocutaneous disease 6
When to Consider Intravenous Therapy
- The CDC recommends escalating to IV acyclovir for patients with severe disease requiring hospitalization, immunocompromised status, or disseminated infection or CNS involvement 6, 7
- For severe mucocutaneous HSV requiring hospitalization, the recommended dose is acyclovir 5-10 mg/kg IV every 8 hours for 7-14 days 6, 7
Treatment Duration and Monitoring
- The American Academy of Pediatrics recommends continuing treatment for 7-14 days depending on clinical response, with 7-10 days typically sufficient for immunocompetent children with localized disease 6
Important Clinical Considerations
- The CDC recommends ensuring adequate hydration, as acyclovir is primarily renally excreted and requires dose adjustment in renal insufficiency 6
- The CDC also recommends monitoring for neutropenia, which is the most common toxicity in children receiving acyclovir 6
Alternative Considerations
- For immunocompromised patients, the CDC recommends considering higher doses of acyclovir (400 mg orally 3-5 times daily) and longer treatment duration (14 days or until complete resolution) 6, 7
- The CDC also recommends being vigilant for acyclovir resistance if lesions persist despite therapy in immunocompromised patients 6, 7
CDC‑Recommended Acyclovir Dosing for Children and Management of Resistant HSV in Immunocompromised Patients
Pediatric Oral Acyclovir Dosing
Mild oral HSV infection in children < 45 kg: The CDC advises oral acyclovir 20 mg/kg three times daily (maximum 400 mg per dose) for a duration of 5–10 days. 8
Moderate to severe oral HSV infection in children: Initiate intravenous acyclovir 5–10 mg/kg every 8 hours; once lesions begin to regress, transition to oral acyclovir and continue until complete healing. 8
Treatment of Acyclovir‑Resistant HSV in Immunocompromised Patients
- Resistant HSV: For immunocompromised patients with lesions unresponsive to acyclovir, the CDC recommends foscarnet 40 mg/kg intravenously three times daily or 60 mg/kg intravenously twice daily. 8
Intravenous Acyclovir Therapy for Severe Genital Herpes
Indications for Intravenous Therapy
- The CDC recommends escalating to intravenous acyclovir for patients with severe genital herpes requiring hospitalization (e.g., extensive mucocutaneous involvement or inability to tolerate oral medication) 9, 10.
- The CDC advises intravenous therapy for disseminated HSV infection involving visceral organs such as hepatitis, pneumonitis, or encephalitis 9.
- The CDC specifies that immunocompromised individuals (e.g., those with HIV infection, organ transplantation, or receiving chemotherapy) who experience prolonged, extensive outbreaks should receive intravenous acyclovir 9, 10.
Dosing and Duration
- The CDC recommends a standard intravenous dose of acyclovir 5–10 mg/kg every 8 hours for severe genital herpes 9, 10.
- Treatment should be continued for 5–7 days or until clear clinical improvement is observed, whichever occurs first 9, 10.
Transition to Oral Therapy
- Once lesions begin to regress and systemic symptoms resolve, the CDC advises switching to oral acyclovir 400 mg three times daily until complete healing 9, 10.
- An alternative oral regimen endorsed by the CDC is acyclovir 200 mg five times daily, also continued until full resolution of lesions 9, 10.
Contraindicated Use of Topical Therapy
- The CDC cautions that topical acyclovir is ineffective for severe or systemic genital herpes and should not be used in place of systemic therapy 10.