Treatment of Chickenpox (Varicella)
For otherwise healthy children under 13 years, supportive care alone is recommended, while oral acyclovir should be initiated within 24 hours of rash onset for adolescents ≥13 years, immunocompromised patients, pregnant women with complications, and children with chronic skin or lung disorders. 1, 2
Risk-Stratified Treatment Algorithm
Healthy Children (<13 years)
- Supportive care only is recommended for immunocompetent children without underlying conditions 1, 2
- No antiviral therapy is indicated unless complications develop 3
- Symptomatic treatment includes antipyretics (avoid aspirin due to Reye's syndrome risk), antihistamines for pruritus, and maintaining hydration 4
Adolescents and Adults (≥13 years)
- Oral acyclovir 800 mg four times daily for 5 days should be initiated within 24 hours of rash onset 1, 5
- Treatment beyond 24 hours loses significant efficacy 1
- Adults face substantially higher complication rates with case-fatality rates of 21.3 per 100,000 versus 0.8 per 100,000 in young children 1
Immunocompromised Patients
- Intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days must be initiated immediately upon diagnosis, ideally within 24 hours 1, 2, 5
- This includes HIV-infected patients, transplant recipients, cancer patients on chemotherapy, and those receiving high-dose corticosteroids 1
- IV acyclovir reduces dissemination, visceral complications, and mortality in this high-risk population 6
Special Populations Requiring Oral Acyclovir
- Children with chronic cutaneous disorders (e.g., eczema): 20 mg/kg (maximum 800 mg) four times daily for 5 days 1, 2, 5
- Children with chronic pulmonary disorders: same dosing as above 3, 2
- Patients on long-term salicylate therapy: oral acyclovir at standard doses 3, 2
- Pregnant women with serious complications (e.g., pneumonia): intravenous acyclovir 3, 1
Post-Exposure Prophylaxis
Vaccination Strategy
- Varicella vaccine within 3 days (up to 5 days) of exposure is >90% effective at preventing disease in susceptible immunocompetent individuals 1, 2
- This is the preferred method for post-exposure prophylaxis in eligible patients 3
Varicella-Zoster Immune Globulin (VZIG)
- Administer within 96 hours of exposure (extended to 10 days per recent guidelines) for high-risk individuals who cannot receive vaccine 1, 2
- Indicated for:
- Dosing: 125 IU/10 kg body weight intramuscularly, maximum 625 IU 1
- Critical pitfall: VZIG may prolong incubation period to 28 days, requiring extended monitoring 2
Alternative Prophylaxis
- If VZIG unavailable: acyclovir 20 mg/kg (maximum 800 mg) four times daily for 5-7 days, initiated 7-10 days after exposure 2
Infection Control Measures
- Isolate patients until all lesions are crusted, typically 5-7 days after rash onset 1, 2
- Patients are contagious from 1-2 days before rash until all lesions crust 3
- Healthcare settings require airborne and contact precautions 1
- Unvaccinated healthcare personnel without immunity should be furloughed from days 10-21 after exposure 2
Critical Pitfalls to Avoid
- Do not initiate acyclovir >24 hours after rash onset in immunocompetent patients—efficacy is significantly reduced 1
- Never use acyclovir prophylactically in otherwise healthy individuals after exposure—vaccination is the method of choice 3, 1
- Avoid aspirin in children with varicella due to Reye's syndrome risk 4
- Do not discharge high-risk newborns (maternal varicella 5 days before to 2 days after delivery) without VZIG administration 1
- If varicella develops despite VZIG, antiviral therapy must be instituted immediately 1
Dosing Adjustments for Renal Impairment
For patients with creatinine clearance 0-10 mL/min/1.73 m²: