What is the recommended treatment for chickenpox?

Treatment of Chickenpox

For immunocompetent patients, oral acyclovir 800 mg four times daily for 5 days (or 20 mg/kg/dose up to 800 mg for children) should be initiated within 24 hours of rash onset for adolescents ≥13 years, adults, and high-risk groups, while immunocompromised patients require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days. 1, 2, 3

Who Requires Antiviral Treatment

Mandatory treatment groups include:

• Adolescents and adults ≥13 years of age 1, 4
• All immunocompromised patients (require IV formulation) 1, 4
• Children with chronic cutaneous or pulmonary disorders 1, 4
• Patients on long-term salicylate therapy 1, 4
• Patients receiving corticosteroid therapy 1, 4

Treatment is most effective when started within 24 hours of rash onset, with a clear gradation in clinical response correlating to timing—earlier initiation produces significantly better outcomes. 5, 6 Starting therapy on day 2 of rash still provides some benefit, but efficacy diminishes substantially after 24 hours. 5

Oral Acyclovir Dosing

For children <40 kg:

• 20 mg/kg per dose (maximum 800 mg) orally 4 times daily for 5 days 1, 3

For adults and children >40 kg:

• 800 mg orally 4 times daily for 5 days 1, 3

Five days of therapy is sufficient—extending to 7 days provides no additional clinical benefit. 5 The FDA-approved regimen specifies dosing every 4 hours while awake (5 times daily). 3

Intravenous Acyclovir for Severe Disease

Immunocompromised patients and those with severe disease require:

• 10 mg/kg IV every 8 hours for 7-10 days 1, 2, 7
• Some experts dose children >1 year based on body surface area: 500 mg/m²/dose IV every 8 hours 2

IV acyclovir halts disease progression in immunocompromised hosts and is potentially life-saving, as chickenpox in this population can be fatal. 7

Renal Dosing Adjustments

For creatinine clearance 10-25 mL/min: 800 mg every 8 hours 3

For creatinine clearance 0-10 mL/min: 800 mg every 12 hours 3

Hemodialysis patients: Administer an additional dose after each dialysis session due to 60% reduction in plasma concentrations during 6-hour dialysis. 3

Post-Exposure Prophylaxis

Varicella zoster immune globulin (VZIG) is the preferred prophylaxis for high-risk exposed individuals:

• Administer as soon as possible, up to 10 days after exposure (ideally within 96 hours) 1, 4
• Indicated for susceptible immunocompromised patients 1, 4
• Indicated for pregnant women without evidence of immunity 1
• Indicated for neonates born to mothers with varicella 5 days before to 2 days after delivery 1
• Indicated for premature infants <28 weeks gestation or <1,000 g regardless of maternal immunity 1

If VZIG is unavailable:

• Oral acyclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 1, 2

Critical caveat: Acyclovir is NOT indicated for routine prophylaxis in healthy individuals after exposure. 2 Delay varicella vaccination 5 months after VZIG administration. 1

Infection Control Measures

Isolate patients until all lesions have crusted over. 1, 4 This is the standard endpoint for contagiousness.

Healthcare workers without immunity exposed to VZV should be furloughed from days 10-21 after exposure. 1, 4

Special Populations

Pregnant women:

• Acyclovir is FDA pregnancy category B 2
• Routine use during pregnancy is not generally recommended 2
• For serious viral-mediated complications, IV acyclovir should be considered 2
• VZIG is recommended for VZV-susceptible pregnant women within 96 hours of exposure 8

HIV-infected children:

• Varicella vaccination is recommended for asymptomatic, non-immunosuppressed children (immunologic category 1) at 12-15 months 8, 1
• Live varicella vaccine is contraindicated in other HIV-infected children due to risk of disseminated infection 8, 1

Vaccination Considerations for Contacts

Vaccinate susceptible household contacts of immunocompromised patients to prevent transmission, provided they are HIV-seronegative and have no history of chickenpox. 8, 4 This creates a protective barrier around vulnerable individuals.

Important Clinical Caveats

Acyclovir does not eradicate latent virus or affect subsequent risk of herpes zoster (shingles). 2 Antibody titers after infection in treated children do not differ substantially from untreated patients. 2

Viral resistance has not been a clinical problem—viruses shed during oral acyclovir therapy retain normal susceptibility and thymidine kinase function. 5 However, the effect on latent virus resistance remains unassessed. 5

Antibody titers are unreliable in patients with nephrotic-range proteinuria or those receiving IVIG for determining immunity status. 1

Disease severity increases with age, and secondary household cases tend to be more severe than primary cases, supporting treatment of adolescents, adults, and secondary family cases. 7