Treatment of Varicella Zoster (Chickenpox)
For otherwise healthy children with chickenpox, oral acyclovir is NOT routinely recommended, but should be considered for persons at increased risk for moderate to severe disease, including those aged >12 years, persons with chronic cutaneous or pulmonary disorders, those receiving long-term salicylate therapy, and those on corticosteroids. 1
Treatment Recommendations by Patient Population
Healthy Children (<12 years)
- Acyclovir is not recommended for routine administration in otherwise healthy children, as the clinical benefit does not justify routine use 1
- When administered within 24 hours of rash onset, acyclovir decreases the number of days new lesions appear, duration of fever, and severity of symptoms, but does NOT decrease transmission or reduce school absence 1
- Antibody titers after infection in children receiving acyclovir do not differ substantially from untreated children 1
High-Risk Patients Requiring Treatment
Oral acyclovir should be considered for:
- Persons aged >12 years 1
- Persons with chronic cutaneous or pulmonary disorders 1
- Persons receiving long-term salicylate therapy 1
- Persons receiving short, intermittent, or aerosolized courses of corticosteroids 1
- Secondary household contacts (certain experts recommend treatment for secondary case-patients living in the same household) 1
Dosing Regimen
For children aged 2 years and older:
- 20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days 2
- Children over 40 kg should receive the adult dose 2
For adults and children over 40 kg:
- 800 mg orally 4 times daily for 5 days 2
Critical timing: Therapy should be initiated at the earliest sign or symptom of chickenpox, ideally within 24 hours of rash onset 1, 3, 2
Immunocompromised Patients
- Intravenous acyclovir is indicated for treatment of varicella-zoster infections in immunocompromised patients 2
- Antiviral therapy should be administered regardless of timing due to higher risk of disseminated infection 3
- Treatment accelerates healing and reduces varicella-associated morbidity and mortality when administered within 24 hours of rash onset 1
Pregnant Women
- Acyclovir is FDA Pregnancy Category B with no increased birth defects documented in 596 first-trimester exposures 1, 3
- Routine use of oral acyclovir is NOT recommended for pregnant women because risks and benefits to fetus and mother were unknown at the time of guideline publication 1
- Intravenous acyclovir should be considered for serious viral-mediated complications such as pneumonia 1
Post-Exposure Prophylaxis
First-Line: Varicella-Zoster Immune Globulin (VZIG)
- VZIG is strongly preferred for pregnant women and immunocompromised persons exposed to varicella 1, 3
- Administer within 96 hours of exposure for maximum benefit 1, 3
- Dosing: 125 units/10 kg body weight, up to maximum of 625 units (five vials), minimum dose 125 units 1
- VZIG may extend incubation period from 10-21 days to >28 days 1
Alternative: Acyclovir Prophylaxis
- If VZIG is unavailable or >96 hours post-exposure: acyclovir 20 mg/kg (maximum 800 mg) four times daily for 5-7 days, initiated 7-10 days after exposure 1, 3
- Acyclovir is NOT indicated for prophylactic use among otherwise healthy children, adolescents, or adults without evidence of immunity after exposure—vaccination is the method of choice 1
Important Caveats
Treatment Efficacy Window
- There is no information about efficacy of therapy initiated more than 24 hours after onset of signs and symptoms 2
- This 24-hour window for chickenpox differs from the 72-hour window for herpes zoster treatment 3
Renal Impairment
- Dose adjustments are mandatory in patients with renal impairment to prevent acute renal failure 2
- For creatinine clearance 0-10 mL/min/1.73 m²: reduce 800 mg dose to every 12 hours instead of every 4 hours 2