What is the treatment for chicken pox (varicella)?

Treatment of Chickenpox (Varicella)

For otherwise healthy children and adults with chickenpox, oral acyclovir is the recommended antiviral treatment when therapy is indicated, administered at 20 mg/kg (maximum 800 mg) four times daily for 5 days, ideally started within 24 hours of rash onset. 1, 2

When to Initiate Antiviral Treatment

Treatment should be started within 24 hours of rash onset for maximum effectiveness. 1, 2

• Healthy children aged 2-18 years: Acyclovir 20 mg/kg per dose (maximum 800 mg) orally 4 times daily for 5 days 2
• Adults and children over 40 kg: Acyclovir 800 mg orally 4 times daily for 5 days 2
• Adolescents and adults tend to have more severe disease and benefit more from treatment 2

Treatment initiated beyond 24 hours may still provide benefit, though efficacy data are limited for therapy started later in the disease course. 2

Special Populations Requiring Treatment

Immunocompromised Patients

Immunocompromised patients require intravenous acyclovir at 10 mg/kg IV every 8 hours. 1, 2 These patients are at significantly higher risk for severe, disseminated disease and complications. 3

Infants Under 12 Months

For otherwise healthy infants with uncomplicated chickenpox, supportive care alone is the primary treatment, as antiviral therapy is not routinely indicated. 3 However, acyclovir should be considered if the infant is immunocompromised or receiving immunosuppressive therapy. 3

Supportive Care Measures

All patients should receive symptomatic treatment regardless of antiviral use:

• Relieve itching with lukewarm baths containing colloidal oatmeal 3
• Maintain adequate hydration 2
• Use acetaminophen (paracetamol) for fever, NOT NSAIDs 4

Critical Pitfall: Avoid NSAIDs

NSAIDs should be avoided in chickenpox due to increased risk of severe bacterial skin infections (necrotizing fasciitis). 4 Use acetaminophen/paracetamol instead for fever control.

Post-Exposure Prophylaxis

For Susceptible Exposed Individuals

Varicella zoster immune globulin (VZIG) should be administered within 96 hours of exposure to susceptible individuals at high risk for severe disease. 5, 3

High-risk groups include:

• Immunocompromised patients 5
• Pregnant women 5
• Neonates 5

Alternative approach: If VZIG is unavailable, a 7-day course of oral acyclovir can be initiated 7-10 days after exposure. 1 Current UK guidelines recommend acyclovir starting 7 days after exposure rather than VZIG for post-exposure prophylaxis in immunosuppressed patients. 5

Vaccination Post-Exposure

Varicella vaccine administered within 3-5 days of exposure may prevent or attenuate infection in susceptible individuals without contraindications. 3

Dosing Adjustments

Renal Impairment

Dosage must be adjusted based on creatinine clearance: 2

• CrCl >10 mL/min: 800 mg every 4 hours (5 times daily)
• CrCl 10-25 mL/min: 800 mg every 8 hours
• CrCl 0-10 mL/min: 800 mg every 12 hours
• Hemodialysis patients: Additional dose after each dialysis session 2

Clinical Outcomes with Treatment

Acyclovir treatment in controlled trials demonstrated: 2

• Shortened time to 50% healing
• Reduced maximum number of lesions
• Decreased median number of vesicles
• Reduced proportion of patients with fever, anorexia, and lethargy by day 2
• Did not affect varicella-zoster virus-specific immune responses at 1 month or 1 year

Isolation and Infection Control

Patients should remain isolated until all lesions have crusted over (typically 5-7 days) to prevent transmission. 3 Chickenpox is extremely contagious, with over 90% of susceptible exposed persons becoming infected. 6

Important Caveats

• Acyclovir is NOT a cure and does not prevent future herpes zoster (shingles) 2
• No data support corticosteroid use in chickenpox treatment 7
• Adequate hydration must be maintained during treatment to prevent nephrotoxicity 2
• Treatment is most effective when initiated within the first 48 hours of rash onset 2