Acyclovir 800 mg Dosing for Herpes Simplex Virus Infections
Acyclovir 800 mg orally twice daily for 5 days is the recommended dosing regimen for treating recurrent episodes of genital herpes simplex virus infections, offering equivalent efficacy to more frequent dosing schedules with superior convenience and adherence. 1, 2
Clinical Context and Indication
The 800 mg twice-daily dosing represents one of three equally effective treatment options for recurrent HSV episodes, alongside 200 mg five times daily or 400 mg three times daily, all administered for 5 days. 1 The FDA-approved labeling confirms this dosing as standard intermittent therapy for recurrent genital herpes. 2
Specific Dosing Regimens by Clinical Scenario
Recurrent Genital Herpes (Episodic Treatment)
- Acyclovir 800 mg orally twice daily for 5 days is the most convenient option among three equally effective regimens 1, 3, 2
- Alternative regimens include 200 mg five times daily or 400 mg three times daily for 5 days 1, 3
- Treatment must be initiated during prodrome or within 2 days of lesion onset for maximum benefit 4, 3, 5
First Clinical Episode (Primary Infection)
- The 800 mg twice-daily dosing is not recommended for first episodes 1
- Use 200 mg five times daily for 7-10 days until clinical resolution 1, 4, 3
- Alternatively, 400 mg three times daily for 7-10 days is acceptable 3
Herpes Zoster (Shingles)
- Acyclovir 800 mg orally five times daily for 7-10 days is the FDA-approved regimen 2
- This higher frequency dosing (800 mg five times daily) is superior to 400 mg five times daily for zoster 6
Chronic Suppressive Therapy
- Acyclovir 400 mg orally twice daily is the standard suppressive regimen, not 800 mg 1, 4, 2
- This reduces recurrence frequency by at least 75% in patients with six or more episodes per year 1, 4
- After 1 year of continuous suppression, discontinue to reassess recurrence rate 1, 3, 2
Recurrent Oral Herpes (Herpes Labialis/Cold Sores)
- Acyclovir 800 mg orally twice daily for 5 days demonstrates shortened symptom duration (8.1 vs 12.5 days with placebo, p=0.02) and reduced pain duration (2.5 vs 3.9 days, p=0.02) 5
- Alternative regimens include 400 mg three to five times daily for 5 days 5, 7
Important Clinical Caveats
Timing of Initiation
- Early treatment is critical: therapy must begin during prodrome or within 1-2 days of lesion onset 4, 3, 5
- Most immunocompetent patients with recurrent disease experience limited benefit when treatment is delayed 1, 5
Topical Therapy Should Be Avoided
- Topical acyclovir is substantially less effective than oral formulations and provides no improvement in systemic symptoms 1, 4, 3
- Oral therapy is the standard of care for all mucocutaneous HSV infections 8, 7
Limitations of Antiviral Therapy
- Acyclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after discontinuation 1, 5, 8
- Suppressive therapy does not totally eliminate asymptomatic viral shedding or transmission potential 1, 4
Special Populations
Immunocompromised Patients
- May require more aggressive therapy with prolonged treatment courses 1, 4, 3
- Consider higher doses or intravenous therapy (5-10 mg/kg IV every 8 hours) for severe disease 1, 2
Renal Impairment
- For creatinine clearance 10-25 mL/min: reduce 800 mg dosing to every 8 hours 2
- For creatinine clearance 0-10 mL/min: reduce to 800 mg every 12 hours 2
- Administer additional dose after hemodialysis 2
Pregnancy Considerations
- Women of childbearing age should inform obstetric providers about HSV infection due to neonatal transmission risk 4, 3