Treatment of Chicken Pox (Varicella)
Acyclovir is the first-line treatment for chicken pox, with dosing based on age and severity of infection. 1, 2
Treatment Regimens
For Children
- Oral acyclovir 20 mg/kg per dose (maximum 800 mg/dose) 4 times daily for 5 days, ideally started within 24 hours of rash onset 1
- Children over 40 kg should receive the adult dose 1
- Treatment should be initiated at the earliest sign or symptom of chickenpox for maximum effectiveness 1, 3
For Adults
- Oral acyclovir 800 mg 4 times daily for 5 days 1
- Treatment is most effective when started within the first 24-48 hours after rash onset 1, 4
For Immunocompromised Patients
- Intravenous acyclovir is indicated for immunocompromised patients with varicella infection 1, 5
- Dosage: 10 mg/kg IV every 8 hours 2, 5
- More aggressive treatment is necessary due to higher risk of disseminated disease 6
Post-Exposure Prophylaxis
- For susceptible individuals (no history of chickenpox or varicella vaccination) exposed to varicella, varicella-zoster immune globulin (VZIG) should be administered within 96 hours of exposure 7
- If VZIG is not available, a 7-day course of acyclovir starting 7-10 days after exposure may be considered 7, 2
- HIV-infected children and adults who are susceptible to VZV should avoid exposure to persons with chickenpox or shingles 7
Special Considerations
Renal Impairment
- Dosage adjustment is necessary for patients with renal impairment 1
- For creatinine clearance 10-25 mL/min/1.73m², adjust 800 mg dose to every 8 hours 1
- For creatinine clearance <10 mL/min/1.73m², adjust 800 mg dose to every 12 hours 1
Pregnancy
- Acyclovir is classified as Pregnancy Category B 1
- VZIG is not contraindicated during pregnancy and should be given to VZV-susceptible pregnant women after exposure 7
Clinical Pearls and Pitfalls
- Early treatment (within 24 hours of rash onset) is crucial for maximizing effectiveness 1, 3
- There is no information about the efficacy of therapy initiated more than 24 hours after onset of signs and symptoms in normal hosts 1
- Adequate hydration should be maintained during acyclovir treatment 1
- Symptomatic treatment alone is usually adequate for immunocompetent children with uncomplicated chickenpox 8, 9
- Antiviral therapy has been shown to decrease the number of lesions, shorten the duration of new lesion formation, and reduce systemic symptoms like fever and fatigue 3, 4