What is the recommended dose and duration of acyclovir for treating herpes infections?

Acyclovir Dosing for Herpes Infections

For treating herpes infections, acyclovir should be dosed at 200 mg orally five times daily for 5-14 days for genital herpes, 400 mg orally three times daily for 5-10 days for orolabial herpes, and 800 mg orally five times daily for 7-10 days for herpes zoster. 1, 2

Dosing Guidelines by Infection Type

Genital Herpes

• Initial episode:
  • 200 mg orally every 4 hours, 5 times daily for 10 days 1
  • For immunocompromised patients: Consider IV acyclovir for severe cases 2

Orolabial Herpes (Cold Sores)

• Treatment:
  • Adults: 400 mg orally three times daily for 5-10 days 2
  • Children: 20 mg/kg body weight (maximum 400 mg/dose) orally three times daily for 5-10 days 2

Herpes Zoster (Shingles)

• Treatment: 800 mg orally every 4 hours, 5 times daily for 7-10 days 1, 3
  • Higher dose (800 mg) is significantly more effective than lower dose (400 mg) for zoster 3

Severe Mucocutaneous Lesions

• Initial treatment: IV acyclovir until lesions begin to regress, then switch to oral therapy 2
• Complete treatment: Continue until lesions have completely healed 2

Special Populations

Immunocompromised Patients

• HIV-infected patients: Longer duration may be required; short-course therapy (1-3 days) should not be used 2
• Severe cases: Consider IV acyclovir initially 2

Children

• Moderate to severe gingivostomatitis:
  • Initial: Acyclovir 5-10 mg/kg IV three times daily
  • Switch to oral therapy when lesions begin to regress
  • Continue until lesions completely heal 2
• Mild gingivostomatitis: Acyclovir 20 mg/kg (max 400 mg/dose) orally three times daily for 5-10 days 2

Suppressive Therapy

For patients with frequent recurrences (≥6 episodes per year):

• Standard regimen: 400 mg orally twice daily for up to 12 months 1, 4
• Alternative regimens: 200 mg 3-5 times daily 1
• After 1 year, re-evaluate frequency and severity of infections 1

Renal Dose Adjustments

Creatinine Clearance	200 mg Regimen	400 mg Regimen	800 mg Regimen
>10 mL/min	200 mg q4h	400 mg q12h	800 mg q4h
0-10 mL/min	200 mg q12h	200 mg q12h	800 mg q12h

For patients on hemodialysis: Administer an additional dose after each dialysis session 1

Important Clinical Considerations

1. Treatment initiation: Begin therapy at earliest signs or symptoms for maximum efficacy 4, 5

   • Starting within first 3 days of symptoms shortens duration of episode 6

2. Treatment failure: Suspect resistance if lesions don't begin to resolve within 7-10 days of therapy 2

   • For suspected acyclovir-resistant HSV, obtain viral culture and consider foscarnet 2

3. Monitoring:

   • For high-dose IV acyclovir: Monitor renal function at initiation and 1-2 times weekly 2
   • Ensure adequate hydration during treatment 4

4. Common pitfalls:

   • Topical acyclovir alone is substantially less effective than systemic therapy 4
   • Short-course therapy is ineffective in immunocompromised patients 2
   • Treatment does not prevent virus latency or recurrent disease 5

The evidence clearly demonstrates that appropriate dosing and duration of acyclovir therapy significantly reduces viral shedding, speeds healing, and decreases pain associated with herpes infections 7, 5. While acyclovir effectively treats acute episodes, it does not eliminate the risk of future recurrences, which may require suppressive therapy in patients with frequent outbreaks 2, 4.