What is the recommended dose of acyclovir (antiviral medication) for an otherwise healthy adult with oral herpes?

Acyclovir Dosing for Oral Herpes in Healthy Adults

For otherwise healthy adults with oral herpes (herpes labialis/cold sores), the recommended dose is acyclovir 400 mg orally three times daily for 5 days, initiated during the prodrome or within 2 days of lesion onset. 1

Standard Treatment Regimens

The CDC provides three equally effective dosing options for treating recurrent oral herpes outbreaks, all for 5-day duration: 1

• Acyclovir 400 mg orally 3 times daily for 5 days (most practical regimen) 1, 2
• Acyclovir 200 mg orally 5 times daily for 5 days 1, 3
• Acyclovir 800 mg orally 2 times daily for 5 days 1, 3

Critical Timing Considerations

Treatment must be initiated during the prodrome or within 2 days of lesion onset for maximum benefit. 1 Starting therapy after this window significantly reduces effectiveness, and most immunocompetent patients with recurrent disease experience limited benefit from delayed therapy. 1

Severe Oral Herpes (Gingivostomatitis)

For moderate to severe symptomatic gingivostomatitis requiring more aggressive treatment: 4

• Start with acyclovir 5-10 mg/kg IV every 8 hours 4
• After lesions begin to regress, switch to oral acyclovir and continue until complete healing 4

For mild symptomatic gingivostomatitis:

• Acyclovir 20 mg/kg (maximum 400 mg/dose) orally 3 times daily for 5-10 days 4

Alternative Agents

If improved convenience is desired: 1

• Valacyclovir 2 g orally twice daily for 1 day (single-day therapy with comparable efficacy) 1
• Famciclovir 1500 mg single dose (significantly reduces healing time: 4.4 days vs 6.2 days with placebo) 1

Expected Clinical Outcomes

With the 800 mg twice-daily regimen, patients can expect: 1

• Shorter duration of symptoms (8.1 days vs 12.5 days with placebo)
• Reduced mean pain duration (2.5 days vs 3.9 days with placebo)
• Fewer lesions developing (7% vs 26% with placebo)

Essential Patient Counseling

Patients must understand that acyclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after discontinuation. 1 Patients should abstain from activities that might spread the virus while lesions are present, though transmission can occur during asymptomatic periods. 1

Suppressive Therapy for Frequent Recurrences

For patients with frequently recurrent oral herpes (≥6 episodes per year), chronic suppressive therapy is an option: 5

• Acyclovir 400 mg orally twice daily results in 53% reduction in clinical recurrences and 71% reduction in virus culture-positive recurrences 5
• After 1 year of suppressive therapy, re-evaluate the frequency and severity to assess need for continuation 3

Common Pitfall to Avoid

The most critical error is delayed treatment initiation. Oral antiviral medications are significantly more effective than topical formulations, but only when started early. 1 Topical acyclovir provides minimal benefit compared to systemic therapy. 1, 2