What is the recommended management for varicella (chickenpox)?

Management of Varicella (Chickenpox)

Primary Treatment Recommendation

For otherwise healthy children with varicella, supportive care alone is appropriate, while oral acyclovir (20 mg/kg four times daily for 5 days) should be initiated within 24 hours of rash onset for persons ≥13 years, immunocompromised patients (who require IV acyclovir 10 mg/kg every 8 hours), pregnant women with complications, and children with chronic cutaneous or pulmonary disorders. 1, 2

Risk-Stratified Treatment Algorithm

Immunocompetent Children (<13 years)

• Supportive care only for otherwise healthy children 1
• Oral acyclovir (20 mg/kg per dose, maximum 800 mg, four times daily for 5 days) should be considered for: 1, 3
  • Children with chronic cutaneous disorders (e.g., eczema)
  • Children with chronic pulmonary disorders (e.g., asthma on chronic therapy)
  • Children receiving long-term salicylate therapy
  • Secondary household cases (some experts recommend)

Adolescents and Adults (≥13 years)

• Oral acyclovir 800 mg four times daily for 5 days if initiated within 24 hours of rash onset 1, 2, 3
• Treatment reduces duration and severity of illness in this age group 1
• Efficacy is substantially reduced if initiated >24 hours after rash onset 2

Immunocompromised Patients

• Intravenous acyclovir 10 mg/kg (or 500 mg/m²) every 8 hours for 7-10 days 1, 2
• Must be initiated within 24 hours of rash onset to reduce morbidity and mortality 2
• Continue until no new lesions appear for 48 hours 1
• For patients not responding to acyclovir: foscarnet 40-60 mg/kg IV three times daily for 7-10 days 1

Pregnant Women

• Supportive care for uncomplicated varicella 1
• Intravenous acyclovir for serious viral-mediated complications (e.g., pneumonia) 1, 2
• Acyclovir is FDA Category B with reassuring safety data from 596 first-trimester exposures showing no increased birth defect rates 1, 2
• Oral acyclovir may be considered for pregnant women at increased risk for moderate-to-severe disease 2

Post-Exposure Prophylaxis

For Susceptible Individuals Without Contraindications

• Varicella vaccine within 3 days of exposure (>90% effective in preventing disease) 1
• Vaccination within 5 days of exposure is approximately 70% effective in preventing varicella and 100% effective in modifying severe disease 1
• Vaccination is the preferred method, not acyclovir prophylaxis 1

For High-Risk Individuals With Contraindications to Vaccination

• Varicella-zoster immune globulin (VZIG) within 96 hours of exposure for: 1, 4
  • Immunocompromised patients
  • Pregnant women without evidence of immunity
  • Newborns whose mothers developed varicella 5 days before to 2 days after delivery
• If VZIG 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 4

Critical Timing Considerations

The 24-hour window is paramount for treatment efficacy 1, 2, 3:

• Acyclovir loses substantial efficacy when initiated >24 hours after rash onset in immunocompetent patients 2
• Immunocompromised patients should receive antiviral therapy regardless of timing due to higher risk of disseminated infection 4
• Treatment should be initiated at the earliest sign or symptom of chickenpox 3

Dosing by Patient Population

Oral Acyclovir Dosing 3

• Children 2-12 years (<40 kg): 20 mg/kg per dose four times daily for 5 days
• Children >40 kg and adults: 800 mg four times daily for 5 days
• Renal impairment: Adjust dosing based on creatinine clearance (see drug label for specific adjustments)

Intravenous Acyclovir Dosing 1

• Children <45 kg: 20 mg/kg (maximum 400 mg) every 8 hours
• Adults and adolescents: 10 mg/kg every 8 hours
• Alternative dosing in children >1 year: 500 mg/m² every 8 hours

Common Pitfalls to Avoid

• Do not use acyclovir prophylactically in otherwise healthy children, adolescents, or adults after varicella exposure—vaccination is the method of choice 1, 2
• Avoid salicylates for 6 weeks after varicella vaccination due to Reye syndrome risk, though no adverse events have been reported 1
• Do not confuse varicella treatment with herpes zoster treatment—zoster has a 72-hour treatment window while varicella has a 24-hour window for optimal efficacy 4
• Do not delay IV acyclovir in immunocompromised patients waiting for laboratory confirmation—clinical diagnosis is sufficient to initiate therapy 2
• Ensure adequate hydration when using high-dose acyclovir to prevent crystalluria and renal complications 3

Infection Control Measures

• Isolate patients until all lesions are crusted (typically 5-7 days after rash onset) 1
• Healthcare personnel with vaccine-related rash should avoid contact with susceptible high-risk persons until lesions resolve or no new lesions appear within 24 hours 1
• Airborne and contact precautions are required in healthcare settings 1