Duration of Acyclovir Therapy for Oral HSV Infections

Standard Regimens for Recurrent Disease

• In immunocompetent patients with recurrent oral HSV lesions, the recommended regimen is acyclovir 800 mg taken twice daily for 5 days; however, therapy should be continued until complete clinical resolution rather than stopping at a preset day count. [CDC MMWR Recommendations] 1

First Clinical Episode (Initial Outbreak)

• For a first clinical episode, which often presents with more severe oral lesions, the guideline advises acyclovir 200 mg administered five times daily for 7–10 days or until lesions heal. [CDC MMWR Recommendations] 2

Immunocompromised Patients

• Patients with compromised immunity (e.g., HIV infection, organ transplantation, chemotherapy) frequently experience prolonged and extensive HSV episodes; they require more aggressive therapy and treatment must be maintained until complete healing.
• In severe cases requiring hospitalization, the recommendation is intravenous acyclovir 5–10 mg/kg every 8 hours for 5–7 days or until clinical resolution. [CDC MMWR Recommendations] 7

Day‑5 Assessment and Decision to Extend Therapy (Immunocompetent)

• If, after 5 days of standard therapy, lesions show partial improvement, the same regimen should be continued until full resolution. [CDC MMWR Recommendations] 3
• When lesions persist beyond 5 days (suggesting either a first episode or unusually severe recurrent disease), the guideline recommends continuing oral acyclovir 800 mg twice daily until all lesions are completely healed. [CDC MMWR Recommendations] 4

Severe Hospitalized Disease (Immunocompetent or Immunocompromised)

• For patients with severe oral HSV disease requiring inpatient care, the advised regimen is IV acyclovir 5–10 mg/kg every 8 hours for 5–7 days or until lesions resolve, after which oral therapy may be continued to ensure complete healing. [CDC MMWR Recommendations] 7

Evidence Summary

• The CDC MMWR recommendations consistently emphasize that HSV therapy should be guided by clinical response rather than a fixed 5‑day course, especially when lesions remain active. [CDC MMWR Recommendations] 4