Do I need to take acyclovir every day or only during a herpes simplex (cold sore) outbreak?

Acyclovir Treatment for Cold Sores: Daily vs. Episodic Therapy

Acyclovir can be taken either episodically (only during outbreaks) or daily as suppressive therapy, depending on the frequency of your cold sore recurrences. 1, 2

Treatment Approach Based on Recurrence Frequency

Episodic Therapy (For Infrequent Outbreaks)

If you experience fewer than 6 outbreaks per year, episodic therapy is generally recommended:

• Start treatment at the first sign of prodrome (tingling, burning) or within 1 day of lesion onset 1

• Recommended dosage options:

  • Acyclovir 400 mg orally three times daily for 5 days
  • Acyclovir 200 mg orally five times daily for 5 days
  • Acyclovir 800 mg orally twice daily for 5 days 1, 2

• Keep medication on hand to start immediately when symptoms begin 1

Suppressive Therapy (For Frequent Outbreaks)

Daily suppressive therapy is recommended if you have 6 or more recurrences per year:

• Reduces recurrence frequency by ≥75% 1
• Recommended dosage:
  • Acyclovir 400 mg orally twice daily 1, 2
  • Alternative: Acyclovir 200 mg orally 3-5 times daily 1

Important Considerations

• Safety profile: Daily suppressive therapy has been documented as safe for up to 6 years 1
• Reassessment: After 1 year of continuous suppressive therapy, consider discontinuing to reassess recurrence frequency 1
• Viral shedding: Suppressive therapy reduces but does not eliminate asymptomatic viral shedding 1
• Single-dose option: For some patients, a single 800 mg dose taken at the first sign of an outbreak may prevent lesions from appearing 3, though this is not part of standard guidelines

Special Populations

• Immunocompromised patients may require higher doses and longer treatment courses 2
• Renal impairment: Dosage adjustment required for creatinine clearance below 25 ml/min 2

Common Pitfalls to Avoid

• Delayed treatment: Starting episodic therapy too late (beyond 1-2 days after onset) significantly reduces effectiveness 1
• Inadequate suppression: Using too low a dose for suppressive therapy in patients with very frequent recurrences (>10 per year) 1
• Premature discontinuation: Stopping suppressive therapy without reassessing recurrence patterns 1

Remember that acyclovir neither eradicates latent virus nor affects subsequent risk after discontinuation 1. The treatment approach should be based on your specific recurrence pattern and adjusted as needed.