What is the recommended treatment for chickenpox?

Treatment of Chickenpox

Primary Treatment Recommendation

For immunocompetent patients, oral acyclovir should be initiated within 24 hours of rash onset at 800 mg four times daily for 5 days in adults and adolescents ≥12 years, while immunocompromised patients require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days. 1, 2

Treatment Algorithm by Patient Population

Immunocompetent Children (2-12 years)

• Children <40-45 kg: Oral acyclovir 20 mg/kg per dose (maximum 800 mg) four times daily for 5 days 1, 2
• Children >40 kg: Oral acyclovir 800 mg four times daily for 5 days 1, 2
• Treatment is not routinely recommended for otherwise healthy children under 13 years unless they meet high-risk criteria 3

Immunocompetent Adolescents and Adults (≥12 years)

• Oral acyclovir 800 mg four times daily for 5 days 1, 2
• This population should be prioritized for treatment as they are at higher risk for complications 1, 4
• Adults have more severe clinical courses and higher susceptibility to complications, making early treatment critical 4, 5

Immunocompromised Patients (All Ages)

• Intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days 1, 6, 2
• Alternative dosing in children >1 year: 500 mg/m²/dose IV every 8 hours 1
• Continue treatment until no new lesions appear for 48 hours 1
• Consider discontinuing immunomodulator therapy if clinically feasible 1

High-Risk Groups Requiring Treatment

Even if immunocompetent, the following groups should receive oral acyclovir therapy:

• Chronic cutaneous or pulmonary disorders (e.g., eczema, asthma) 1, 6
• Long-term salicylate therapy (due to Reye's syndrome risk) 1, 6
• Corticosteroid therapy (short, intermittent, or aerosolized) 1, 6
• Secondary household contacts of infected children 1
• Pregnant women (though not routinely recommended, acyclovir is Category B) 1

Critical Timing Considerations

Treatment must be initiated within 24 hours of rash onset for maximum efficacy. 1, 2, 3

• The evidence demonstrates a clear gradient in treatment efficacy based on timing 1
• Delayed initiation significantly reduces clinical benefit 1
• There is no information about efficacy when therapy is initiated more than 24 hours after onset 2
• Oral acyclovir is only effective if begun within 24 hours of rash onset 3

Post-Exposure Prophylaxis

Varicella-Zoster Immune Globulin (VZIG)

VZIG should be administered as soon as possible, up to 96 hours (some sources state up to 10 days) after exposure to the following groups: 7, 1, 6

• Immunocompromised patients without evidence of immunity 7, 1
• Pregnant women without evidence of immunity 7, 1, 6
• Neonates born to mothers with varicella 5 days before to 2 days after delivery 7, 1, 6
• Premature infants <28 weeks gestation or <1,000 g regardless of maternal immunity 7, 1, 6
• Premature infants >28 weeks gestation whose mothers lack evidence of immunity 7

Acyclovir Prophylaxis

• If VZIG is unavailable for immunocompromised patients: Oral acyclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 1, 6
• Acyclovir is not indicated for prophylactic use in healthy individuals after exposure 1

Important VZIG Considerations

• VZIG may prolong the incubation period by up to one week, extending the monitoring period from 21 to 28 days 7
• VZIG does not prevent viremia, fetal infection, congenital varicella syndrome, or neonatal varicella—its primary indication is to prevent maternal complications 7
• Delay varicella vaccination 5 months after VZIG administration 7, 1, 6

Infection Control Measures

Patient Isolation

• Isolate patients until all lesions have crusted over 1, 6
• Airborne precautions (negative air-flow rooms) and contact precautions should be employed for all patients with varicella 7
• These precautions should be maintained until lesions are dry and crusted 7

Healthcare Worker Management

Healthcare workers without evidence of immunity exposed to VZV should be furloughed from days 10-21 (or 8-21) after exposure 7, 1, 6

• HCP who received 2 doses of vaccine should be monitored daily during days 8-21 (or 10-21) after exposure for fever, skin lesions, and systemic symptoms 7
• HCP who received 1 dose should receive the second dose within 3-5 days after exposure 7
• Unvaccinated HCP should receive postexposure vaccination as soon as possible and be furloughed during days 8-21 (or 10-21) 7

Renal Dosing Adjustments

For patients with renal impairment receiving oral acyclovir 800 mg every 4 hours: 2

• Creatinine clearance >25 mL/min: 800 mg every 4 hours, 5 times daily
• Creatinine clearance 10-25 mL/min: 800 mg every 8 hours
• Creatinine clearance 0-10 mL/min: 800 mg every 12 hours
• Hemodialysis patients: Administer an additional dose after each dialysis session 2

Common Pitfalls and Caveats

• Acyclovir does not eradicate latent virus or affect subsequent risk of herpes zoster 1
• Birth before 1980 is not considered evidence of immunity for healthcare personnel due to nosocomial transmission risk 7
• Routine antibody testing after 2 doses of vaccine is not recommended for HCP management, as commercial assays lack sufficient sensitivity 7
• Live varicella vaccination is contraindicated in immunocompromised patients due to risk of disseminated infection 1, 6
• Five days of therapy is sufficient for immunocompetent patients—a 7-day course provides no additional benefit 1
• Antibody titers after infection in children receiving acyclovir do not differ substantially from untreated patients 1

Vaccination Considerations

• Susceptible household contacts of immunocompromised patients should be vaccinated to prevent transmission 1, 6
• Vaccination within 3-5 days of exposure to rash might modify disease if infection occurred 7
• Vaccination >5 days postexposure still induces protection against subsequent exposures 7