What is the recommended dose of aciclovir (antiviral medication) for the treatment of oral herpes simplex?

Acyclovir Dosing for Oral Herpes Simplex (Cold Sores)

For oral herpes simplex (cold sores), the CDC recommends three equally effective oral acyclovir regimens: 800 mg twice daily for 5 days (most convenient), 400 mg three times daily for 5 days, or 200 mg five times daily for 5 days. 1

Recommended Dosing Options

All three regimens below are equally effective for treating recurrent oral herpes outbreaks 1:

• Acyclovir 800 mg orally twice daily for 5 days - This is the most convenient option with best adherence while maintaining equivalent efficacy 1
• Acyclovir 400 mg orally three times daily for 5 days - Standard middle-ground option 1, 2
• Acyclovir 200 mg orally five times daily for 5 days - Requires most frequent dosing but equally effective 1, 2

The 800 mg twice-daily regimen demonstrates superior clinical outcomes including shorter symptom duration (8.1 days vs 12.5 days with placebo), reduced pain duration (2.5 days vs 3.9 days), and fewer lesions developing (7% vs 26%) 1

Critical Timing for Treatment Initiation

Treatment must be initiated during the prodrome or within 2 days of lesion onset for maximum benefit. 1, 2

• Starting therapy after this 2-day window significantly reduces effectiveness 1, 2
• Most immunocompetent patients with recurrent disease experience limited benefit from delayed therapy 1, 2

Important Clinical Caveats

Oral acyclovir is strongly preferred over topical formulations - topical acyclovir cream is substantially less effective and its use is discouraged by the CDC 2

• Acyclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after discontinuation 1, 2
• Patients should abstain from activities that might spread the virus while lesions are present, though transmission can occur during asymptomatic periods 1, 2

Alternative Shorter Regimens

For patients prioritizing convenience, alternative agents offer shorter treatment courses 1:

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

Special Populations

For immunocompromised patients, more aggressive therapy is required 2, 3:

• Acyclovir 400 mg orally 3-5 times daily, or IV administration may be necessary 2, 3
• Prolonged episodes with extensive disease may require IV acyclovir 5-10 mg/kg every 8 hours 2