What is the recommended dosing of acyclovir (antiviral medication) for the treatment of fever blisters?

Acyclovir Dosing for Fever Blisters (Cold Sores)

For fever blisters (cold sores), the recommended dosing of oral acyclovir is 200 mg five times daily for 5 days, 400 mg three times daily for 5 days, or 800 mg twice daily for 5 days. 1, 2, 3

Standard Treatment Regimens

• Treatment should be initiated during the prodrome or within 2 days of lesion onset for maximum effectiveness 1, 2
• Three equally effective oral acyclovir regimens for episodic treatment of cold sores:
  • 200 mg orally five times daily for 5 days 1, 2, 3
  • 400 mg orally three times daily for 5 days 1, 2, 3
  • 800 mg orally twice daily for 5 days 1, 2, 3

Clinical Considerations

• Early treatment initiation is crucial - starting therapy at the first sign of symptoms provides the greatest benefit 1, 2
• Most immunocompetent patients with recurrent disease experience limited benefit from therapy if treatment is not started early 1, 2
• Oral acyclovir is significantly more effective than topical formulations for treating cold sores 1, 2
• Acyclovir neither eradicates latent virus nor affects subsequent risk, frequency, or severity of recurrences after discontinuation 1, 2

Special Populations

Immunocompromised Patients

• HIV-infected or otherwise immunocompromised patients may require higher doses or longer treatment courses 1, 2
• For immunocompromised patients with cold sores, recommended dosing: acyclovir 400 mg orally three to five times daily until clinical resolution 1
• For severe cases in immunocompromised patients, intravenous therapy may be required: acyclovir 5-10 mg/kg IV every 8 hours 4, 1

Patients with Renal Impairment

• Dose adjustment is necessary for patients with renal impairment 3:
  • For creatinine clearance >10 mL/min/1.73m²: 200 mg every 4 hours, five times daily
  • For creatinine clearance 0-10 mL/min/1.73m²: 200 mg every 12 hours 3

Frequent Recurrences

• For patients with ≥6 recurrences per year, suppressive therapy may be considered 4, 1
• Suppressive dosing: acyclovir 400 mg orally twice daily 1, 3
• After 1 year of continuous suppressive therapy, acyclovir should be discontinued to reassess the patient's recurrence rate 4, 3

Practical Advice

• The 800 mg twice daily regimen may offer better compliance due to reduced frequency of dosing 1, 2
• Patients should avoid close contact while they have active lesions to prevent transmission 1, 2
• Treatment is most effective when started at the earliest sign of an outbreak (tingling, burning, itching) 1, 2
• Patients should be counseled that acyclovir treats symptoms but does not cure the underlying viral infection 1, 2