What is the recommended treatment for adults diagnosed with chickenpox?

Treatment of Chickenpox in Adults

Adults with chickenpox should receive oral acyclovir 800 mg four times daily for 5-7 days, initiated within 24 hours of rash onset for maximum clinical benefit. 1, 2

Timing of Treatment Initiation: Critical Factor

• Treatment must begin within 24 hours of rash onset to achieve maximum efficacy, as delayed initiation significantly reduces clinical benefit 1, 3
• Adults who present 24-48 hours after rash onset still derive some benefit from acyclovir, though responses are attenuated compared to early treatment 3
• The evidence demonstrates a clear gradient in treatment efficacy based on timing, with the greatest reduction in fever duration, constitutional symptoms, and time to cutaneous healing when therapy starts on day 1 3, 4

Standard Dosing for Immunocompetent Adults

• Oral acyclovir 800 mg four times daily (every 4 hours while awake, 5 times daily) for 5-7 days 1, 2
• Five days of therapy is sufficient for immunocompetent patients, as a 7-day course provides no additional clinical benefit 1, 3
• The FDA-approved dosing is 800 mg four times daily for 5 days 2

Immunocompromised Adults: Different Approach Required

Immunocompromised patients require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days (or until no new lesions appear for 48 hours), as chickenpox in this population is potentially fatal 1, 5, 4

• IV therapy is mandatory—oral therapy is inadequate for immunocompromised hosts 4
• Consider discontinuing immunomodulator therapy in severe cases if clinically feasible 1
• Treatment should be initiated as soon as chickenpox is recognized in immunocompromised individuals 4

Dose Adjustments for Renal Impairment

For adults with renal dysfunction receiving the standard 800 mg dose 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

Post-Exposure Prophylaxis for Susceptible Adults

• Varicella-zoster immune globulin (VZIG) should be administered as soon as possible, up to 96 hours after exposure to susceptible immunocompromised adults 1, 5
• If VZIG is unavailable, administer oral acyclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 1, 5
• Pregnant women without evidence of immunity should receive VZIG after exposure 1, 5
• For immunocompetent adults without access to vaccination, a 7-day course of acyclovir starting 7 days after exposure may be considered 1

Infection Control Measures

• Isolate patients until all lesions have crusted over 1, 5
• Healthcare workers without immunity exposed to varicella should be furloughed from days 10-21 after exposure 1, 5

Important Clinical Caveats

• Acyclovir does not eradicate latent virus and does not affect the subsequent risk, frequency, or severity of herpes zoster (shingles) 1
• Chickenpox severity increases with age, making treatment particularly important in adults compared to children 4
• The disease is extremely contagious, with more than 90% of unvaccinated people becoming infected during their lifetime 6
• Acyclovir treatment does not significantly alter antibody titers, so immunity is preserved 1, 7

Common Pitfalls to Avoid

• Do not delay treatment waiting for laboratory confirmation—initiate therapy based on clinical presentation within 24 hours of rash onset 1, 3
• Do not use oral acyclovir in immunocompromised patients—IV therapy is required 4
• Do not assume treatment is futile after 24 hours—some benefit persists when initiated 24-48 hours after rash onset, particularly in high-risk adults 3
• Do not administer live varicella vaccine to immunocompromised patients due to risk of disseminated infection 1, 5