What is the recommended treatment for chickenpox?

Treatment of Chickenpox

For immunocompetent patients, oral aciclovir should be initiated within 24 hours of rash onset at 20 mg/kg (maximum 800 mg) four times daily for 5-7 days, with treatment prioritized for adolescents ≥12 years, adults, and those with chronic conditions, while immunocompromised patients require intravenous aciclovir 10 mg/kg every 8 hours for 7-10 days. 1, 2

Primary Treatment Approach by Patient Population

Immunocompetent Children and Adolescents

• Children <45 kg: Administer oral aciclovir 20 mg/kg per dose (maximum 400-800 mg/dose) 3-4 times daily for 5-10 days 1, 2
• Adolescents ≥12 years and children >40-45 kg: Administer oral aciclovir 800 mg orally 4-5 times daily for 5-7 days 1, 2
• Treatment must be initiated within 24 hours of rash onset for maximum efficacy, as delayed initiation significantly reduces clinical benefit 1, 3

Immunocompetent Adults

• Administer oral aciclovir 800 mg orally 4-5 times daily for 7-10 days 1, 2
• Adults experience more severe disease than children and should be prioritized for treatment 4
• Valacyclovir 20 mg/kg three times daily for 5 days (not exceeding 1 gram three times daily) is an alternative option for pediatric patients aged 2 to <18 years 5

Immunocompromised Patients (Critical Population)

• Intravenous aciclovir is mandatory: 10 mg/kg IV every 8 hours for 7-10 days 1, 2, 6
• Some experts recommend dosing based on body surface area in children >1 year: 500 mg/m²/dose IV every 8 hours 1
• Treatment should be initiated immediately upon recognition, as chickenpox is potentially fatal in this population 4, 7
• Consider discontinuing immunomodulator therapy in severe cases if clinically feasible 6

High-Risk Groups Requiring Antiviral Treatment

Beyond age considerations, the following patients should receive aciclovir therapy:

• Patients with chronic cutaneous or pulmonary disorders 1, 2, 6
• Patients receiving long-term salicylate therapy 1, 2, 6
• Patients on short, intermittent, or aerosolized corticosteroid therapy 1, 6
• Secondary household contacts of infected children 1
• Pregnant women (though routine use is not generally recommended; Category B pregnancy rating) 1

Post-Exposure Prophylaxis

For Susceptible Immunocompromised Patients

• Varicella zoster immune globulin (VZIG) should be administered as soon as possible, up to 96 hours (some sources state up to 10 days) after exposure 2, 6
• If VZIG is unavailable, administer oral aciclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 2, 6

Special Populations Requiring VZIG

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

For Immunocompetent Exposed Individuals

• Aciclovir is not indicated for prophylactic use in healthy individuals after exposure 1
• A 7-day course of aciclovir starting 7 days after exposure may be considered for those without access to vaccination 1

Timing of Treatment Initiation: Critical Consideration

The evidence demonstrates a clear gradient in treatment efficacy based on timing:

• Within 24 hours of rash onset: Maximum clinical benefit with significantly shortened time to cessation of new lesions, faster healing, and reduced systemic symptoms 1, 3, 4
• 24-48 hours after rash onset: Some benefit remains, particularly for adolescents and adults, but efficacy is reduced 3
• >72 hours after rash onset: Efficacy has not been established and treatment is generally not recommended 5

Research shows that patients treated on the first day of rash had the greatest number of significantly shortened event times, with treatment initiated on the second day showing intermediate benefit 3.

Duration of Therapy

• 5 days of therapy is sufficient for immunocompetent patients, as a 7-day course provides no additional benefit 1, 3
• Immunocompromised patients require 7-10 days of IV therapy or until no new lesions appear for 48 hours 1, 2

Infection Control Measures

• Isolate patients until all lesions have crusted over 2, 6
• Healthcare workers without immunity exposed to VZV should be furloughed from days 10-21 after exposure 2, 6

Vaccination Considerations in Treatment Context

• Live varicella vaccination is contraindicated in immunocompromised patients due to risk of disseminated infection 2, 6
• Susceptible household contacts of immunocompromised patients should be vaccinated to prevent transmission 2
• Delay varicella vaccination 5 months after VZIG administration 2
• For patients on immunomodulators unable to receive live vaccination, advise seeking post-exposure prophylaxis if exposed to active chickenpox or herpes zoster 8

Important Clinical Caveats

• Aciclovir does not eradicate latent virus or affect subsequent risk, frequency, or severity of herpes zoster recurrences 1
• Antibody titers after infection in children receiving aciclovir do not differ substantially from untreated patients 1
• Viruses shed during aciclovir therapy retain susceptibility to aciclovir and normal thymidine kinase function, indicating resistance does not develop during short-term treatment 3
• Efficacy of treatment initiated after development of clinical signs beyond papule stage (vesicle or ulcer) has not been established 5

Adjunctive Symptomatic Treatment

• Symptomatic therapy is adequate for most immunocompetent patients without complications 9
• Antibiotics may be required for secondary bacterial infections; Co-Amoxiclav is commonly used in adults and Ceftriaxone in children 9
• The use of corticosteroids remains controversial and should be approached with caution 9