What is the recommended management for healthy adults with chickenpox?

Management of Chickenpox in Healthy Adults

Healthy adults with chickenpox should receive oral acyclovir 800 mg five times daily for 5 days, initiated within 24 hours of rash onset for maximum clinical benefit. 1, 2, 3

Treatment Timing: Critical Window

The evidence demonstrates a clear efficacy gradient based on timing of initiation:

• Initiation within 24 hours of rash onset provides maximum benefit, reducing time to complete crusting from 7.4 to 5.6 days, decreasing maximum lesion count by 46%, and shortening duration of fever and constitutional symptoms 4
• Treatment initiated 25-72 hours after rash onset shows minimal to no clinical benefit in otherwise healthy adults with uncomplicated disease 5, 6, 4
• The gradation in clinical response correlates directly with time from rash onset to treatment initiation, with progressively diminishing returns after the first 24 hours 5

Standard Treatment Regimen

Dosing for adults:

• Acyclovir 800 mg orally 5 times daily (every 4 hours while awake) for 5 days 1, 2, 3
• Five days of therapy is sufficient—a 7-day course provides no additional clinical benefit 2, 5

When to Treat Despite Delayed Presentation

While treatment after 24 hours shows limited benefit in uncomplicated cases, consider treatment beyond the 24-hour window for:

• Adults with chronic cutaneous or pulmonary disorders 2
• Patients on long-term salicylate therapy 2
• Secondary household contacts who develop disease 2
• Any concern for progression to complicated disease 2

Important caveat: The low frequency of serious complications (pneumonia, encephalitis) in healthy adults means the effect of acyclovir on preventing these outcomes remains unproven 4

Post-Exposure Prophylaxis (Before Disease Onset)

For susceptible healthy adults exposed to varicella but not yet symptomatic:

• First-line: Varicella-zoster immune globulin (VZIG) within 96 hours of exposure 7, 1
• Alternative 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 1, 2
• Note: VZIG for healthy adults should be used judiciously—the objective is to modify rather than prevent illness to induce lifelong immunity 7

Renal Dosing Adjustments

For patients with renal impairment, modify dosing per creatinine clearance 3:

• CrCl >25 mL/min: 800 mg every 4 hours (5 times daily)
• CrCl 10-25 mL/min: 800 mg every 8 hours
• CrCl 0-10 mL/min: 800 mg every 12 hours
• Hemodialysis: Administer additional dose after each dialysis session 3

Infection Control

• Isolate patients until all lesions have crusted over 2
• Chickenpox is extremely contagious with >90% transmission rate to susceptible contacts 8

Common Pitfalls to Avoid

• Do not confuse with herpes zoster treatment: Chickenpox has a 24-hour efficacy window, while zoster has a 72-hour window 1, 9
• Do not routinely treat after 24 hours in uncomplicated cases: Late therapy (25-72 hours) shows no clinical benefit in healthy adults 4
• Acyclovir does not eradicate latent virus and has no effect on subsequent herpes zoster risk 2
• Do not use prophylactic acyclovir in healthy individuals after exposure—vaccination or VZIG are appropriate prophylaxis strategies 2

Special Populations

Pregnant women: Acyclovir is FDA Pregnancy Category B with no documented increased birth defects in 596 first-trimester exposures; VZIG is strongly preferred for post-exposure prophylaxis 1, 2

Immunocompromised patients: Require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days regardless of timing, due to risk of disseminated infection 1, 2