Duration of Acyclovir Treatment for HSV and VZV Infections
The duration of acyclovir treatment varies by indication, with chronic suppressive therapy for recurrent genital herpes being safe and effective for up to 12 months, followed by re-evaluation to assess the need for continued therapy. 1
Treatment Duration by Indication
Genital Herpes (HSV)
Initial Episode
- First clinical episode: 200 mg orally 5 times daily for 7-10 days or until clinical resolution 2
- First clinical episode of herpes proctitis: 400 mg orally 5 times daily for 10 days or until clinical resolution 2
Recurrent Episodes
- 200 mg orally 5 times daily for 5 days, or
- 400 mg orally 3 times daily for 5 days, or
- 800 mg orally 2 times daily for 5 days 2
- Alternative shorter regimen: 800 mg orally 3 times daily for 2 days (shown to significantly reduce duration of lesions, episode, and viral shedding) 3
Chronic Suppressive Therapy
- Standard regimen: 400 mg orally 2 times daily for up to 12 months 1
- Alternative regimen: 200 mg orally 3-5 times daily 2
- After 12 months, therapy should be discontinued to re-evaluate the frequency and severity of recurrences 1
- Long-term studies have documented safety and efficacy for up to 5 years 2
Herpes Zoster (Shingles)
- 800 mg orally every 4 hours, 5 times daily for 7-10 days 1
- Treatment should begin within 72 hours of rash onset, ideally within the first 48 hours 1
- For pregnant women, continue until all lesions have scabbed or completely healed (typically 7-10 days) 4
Chickenpox (Varicella)
- Children (2 years and older): 20 mg/kg per dose orally 4 times daily (maximum 800 mg/dose) for 5 days 1
- Adults and children over 40 kg: 800 mg orally 4 times daily for 5 days 1
- Treatment should be initiated at the earliest sign or symptom of chickenpox 1
Special Populations
Immunocompromised Patients
- May require longer treatment durations than standard recommendations 2
- HIV-infected patients often need extended therapy and closer monitoring 4
- For severe or disseminated disease, IV acyclovir may be necessary 4
Patients with Renal Impairment
Dosage adjustments based on creatinine clearance:
| Creatinine Clearance (mL/min) | Dose Adjustment |
|---|---|
| >25 | Standard dosing |
| 10-25 | Reduce frequency |
| 0-10 | Significant reduction in dose and frequency |
Elderly Patients
- May require dose adjustment due to age-related changes in renal function 4
- Acyclovir plasma concentrations are higher in geriatric patients compared to younger adults 1
Efficacy and Safety Considerations
- Long-term suppressive therapy reduces recurrence frequency by 75-80% in patients with frequent episodes 2, 4
- Acyclovir does not eradicate latent virus or affect subsequent risk after discontinuation 2
- Acyclovir-resistant strains have been isolated in some patients on suppressive therapy but are rare in immunocompetent individuals 2, 5
- After stopping long-term treatment, the frequency of recurrences may be significantly less than the pre-treatment period 6
Clinical Pearls
- Topical acyclovir is substantially less effective than oral therapy for genital herpes and is not recommended 2
- For optimal efficacy in recurrent episodes, treatment should be initiated during the prodrome or within 2 days of lesion onset 2
- After 1 year of suppressive therapy, consider a treatment holiday to reassess recurrence frequency 2, 1
- For immunocompetent patients with infrequent recurrences, episodic therapy may be more appropriate than suppressive therapy 7
The evidence consistently supports that acyclovir is safe for extended periods, with studies documenting safety for up to 5 years of continuous use, though standard practice is to re-evaluate after 12 months of suppressive therapy.