What is the recommended dosage of Acyclovir (antiviral medication) for the treatment of genital herpes, a common Sexually Transmitted Disease (STD)?

Acyclovir Dosing for Genital Herpes (STD)

First Episode Genital Herpes

For first-episode genital herpes, treat with acyclovir 200 mg orally 5 times daily for 7-10 days until clinical resolution. 1, 2

• The FDA-approved regimen is 200 mg every 4 hours, 5 times daily for 10 days 2
• Treatment should be initiated as soon as possible after symptom onset for maximum benefit 1
• For herpes proctitis specifically, use the higher dose of 400 mg orally 5 times daily for 10 days 1
• Higher doses (4 g daily vs 1 g daily) do not provide additional clinical benefit for first episodes 3

Recurrent Episodes

For recurrent genital herpes, use acyclovir 800 mg orally twice daily for 5 days, initiated at the earliest sign of prodrome or within 2 days of lesion onset. 1, 2

Alternative equally effective regimens include:

• Acyclovir 400 mg orally 3 times daily for 5 days 1, 2
• Acyclovir 200 mg orally 5 times daily for 5 days 1, 2

Important caveat: Most immunocompetent patients with recurrent disease experience limited benefit from episodic therapy, particularly when treatment cannot be initiated early 1. The 800 mg twice-daily regimen offers superior convenience and adherence while maintaining equivalent efficacy 4.

Chronic Suppressive Therapy

For patients with frequent recurrences (≥6 episodes per year), prescribe acyclovir 400 mg orally twice daily for continuous suppression. 1, 5, 2

• This regimen reduces recurrence frequency by at least 75% 1, 5
• Alternative regimen: 200 mg orally 3-5 times daily, titrated to the lowest effective dose 1
• After 12 months of continuous therapy, discontinue to reassess the patient's natural recurrence rate 1, 2
• Safety and efficacy documented for up to 5 years of continuous use 1
• Single daily dosing with 800 mg once daily has also demonstrated effectiveness for long-term suppression 6

Severe Disease Requiring Hospitalization

For severe genital herpes with complications (disseminated infection, encephalitis, pneumonitis, hepatitis), administer acyclovir 5-10 mg/kg IV every 8 hours for 5-7 days or until clinical resolution. 1, 5, 2

• This applies to immunocompromised patients who may have prolonged episodes with extensive disease 1
• HIV-infected patients may require more aggressive therapy than standard regimens 1, 5

Renal Impairment Adjustments

Dose adjustment is mandatory in renal impairment, as acyclovir is primarily renally excreted. 5, 2

For the 800 mg every 4 hours regimen:

• CrCl >25 mL/min: 800 mg every 4 hours (5 times daily) 2
• CrCl 10-25 mL/min: 800 mg every 8 hours 2
• CrCl 0-10 mL/min: 800 mg every 12 hours 2

For hemodialysis patients, administer an additional dose after each dialysis session 2.

Critical Clinical Considerations

• Timing is crucial: Treatment must begin during prodrome or within 2 days of lesion onset for meaningful benefit 1, 4
• Patient counseling: Acyclovir does not eradicate latent virus or prevent future recurrences after discontinuation 4
• Transmission risk: Viral shedding and transmission can occur during asymptomatic periods despite therapy 1
• Sexual activity: Advise abstinence while lesions are present 1
• Resistance monitoring: Acyclovir-resistant strains may emerge in immunocompromised patients; if lesions persist despite therapy, consider foscarnet 40 mg/kg IV 3 times daily or 60 mg/kg IV twice daily 5