What is the recommended treatment for a patient presenting with fever blisters, specifically regarding medication options such as Zovirax (acyclovir) or Valtrex (valacyclovir)?

Fever Blister Medication

For fever blisters (herpes labialis), valacyclovir 2 grams twice daily for 1 day is the most effective first-line treatment, offering superior convenience and efficacy compared to traditional acyclovir regimens. 1

First-Line Treatment Options

Valacyclovir is the preferred agent due to its superior bioavailability and convenient dosing:

• Valacyclovir 2g twice daily for 1 day reduces median episode duration by 1.0 day compared to placebo 1
• This short-course, high-dose regimen offers greater convenience, cost benefits, and improved patient adherence 1

Alternative oral antivirals include:

• Famciclovir 1500mg as a single dose 1
• Acyclovir 400mg five times daily for 5 days (requires more frequent dosing) 1, 2

Critical Timing Considerations

Treatment must be initiated at the earliest symptoms (during prodrome or within 24 hours of lesion onset) for maximum efficacy 1:

• Peak viral titers occur in the first 24 hours after lesion onset 1
• Patient-initiated episodic therapy at first symptoms may even prevent lesion development in some cases 1
• Efficacy decreases significantly when treatment is initiated after lesions have fully developed 1

Suppressive Therapy for Frequent Recurrences

Patients experiencing ≥6 recurrences per year should be offered daily suppressive therapy 1:

First-line suppressive options:

• Valacyclovir 500mg once daily (can increase to 1000mg once daily for very frequent recurrences) 1
• Famciclovir 250mg twice daily 1
• Acyclovir 400mg twice daily 1

Efficacy and duration:

• Daily suppressive therapy reduces recurrence frequency by ≥75% 1
• Safety documented for acyclovir up to 6 years; valacyclovir and famciclovir for 1 year 1
• After 1 year of continuous suppressive therapy, consider discontinuation to reassess recurrence rate 1

Important Clinical Considerations

Topical antivirals are NOT effective for treating or suppressing cold sores, as they cannot reach the site of viral reactivation 1:

• Topical treatments provide only modest clinical benefit and are substantially less effective than oral therapy 1

Immunocompromised patients require special consideration:

• Episodes are typically longer and more severe 1
• Higher acyclovir resistance rates (7% versus <0.5% in immunocompetent patients) 1
• May require higher doses or longer treatment durations 1
• For acyclovir-resistant HSV, foscarnet 40mg/kg IV three times daily is the treatment of choice 1

Preventive Counseling

Patients should identify and avoid personal triggers 1:

• Ultraviolet light exposure (use sunscreen on lips)
• Fever and systemic illness
• Psychological stress
• Menstruation

Common Pitfalls to Avoid

• Relying solely on topical treatments when oral therapy is significantly more effective 1
• Starting treatment too late after lesions have fully developed 1
• Failing to consider suppressive therapy in patients with ≥6 recurrences per year who could significantly benefit 1
• Using inadequate dosing regimens instead of short-course, high-dose therapy 1

Safety Profile

All oral antivirals are generally well-tolerated with minimal adverse events 1:

• Common side effects include headache (<10%), nausea (<4%), and diarrhea 1
• Resistance development with episodic use in immunocompetent patients is unlikely (<0.5%) 1