What is the management for fever blisters (herpes simplex labialis)?

Management of Fever Blisters (Herpes Simplex Labialis)

Short-course oral antiviral therapy is the most effective treatment for fever blisters, with valacyclovir 2g twice daily for 1 day being the first-line option due to its high bioavailability and convenient dosing. 1, 2

First-Line Treatment Options

• Oral antivirals are more effective than topical treatments for herpes labialis, decreasing outbreak duration and associated pain by approximately 1 day 1, 3
• Valacyclovir 2g twice daily for 1 day is FDA-approved and recommended as first-line treatment for cold sores 2
• Famciclovir 1500mg as a single dose is an effective alternative, significantly reducing time to healing of primary lesions 4, 5
• Acyclovir 400mg five times daily for 5 days is another option but requires more frequent dosing 4, 3

Treatment Initiation and Timing

• Treatment should be initiated within 24 hours of symptom onset, ideally during the prodromal stage (tingling, burning sensation) 3, 2
• Early initiation is critical as efficacy decreases significantly when treatment begins after lesions have fully developed 1, 2
• Patient-initiated episodic therapy at first symptoms may even prevent lesion development in some cases 4

Treatment Selection Algorithm

1. First choice: Valacyclovir 2g twice daily for 1 day 1, 2
2. Second choice: Famciclovir 1500mg single dose 4, 5
3. Third choice: Acyclovir 400mg five times daily for 5 days 4, 3

Management of Frequent Recurrences

• For patients experiencing six or more recurrences per year, suppressive therapy is indicated 1
• Suppressive therapy options include:
  • Valacyclovir 500mg once daily (can increase to 1000mg daily for very frequent recurrences) 1, 2
  • Famciclovir 250mg twice daily 1
  • Acyclovir 400mg twice daily 1
• Daily suppressive therapy reduces the frequency of herpes recurrences by ≥75% among patients with frequent recurrences 1

Safety Considerations

• Oral antiviral medications are generally well-tolerated with minimal adverse events 4
• Common side effects include headache (most common with valacyclovir), nausea, and diarrhea, which are typically mild to moderate in intensity 4
• Despite increasing use of HSV-specific antiviral agents, the incidence of resistant HSV-1 strains remains low (<0.5% in immunocompetent hosts) 4

Common Pitfalls to Avoid

• Relying solely on topical treatments when oral therapy is more effective 1, 3
• Starting treatment too late, after lesions have fully developed 1, 2
• Inadequate dosing, such as not using short-course, high-dose therapy, which is more effective than traditional longer courses 1, 3
• Failing to consider suppressive therapy in patients with frequent recurrences (≥6 per year) who could significantly benefit 1
• Not discussing potential triggers (e.g., UV light exposure, stress, fever) that patients should avoid even while on therapy 1

Special Considerations

• For immunocompromised patients, higher doses or longer treatment durations may be required 1
• Topical antivirals are not effective for suppressive therapy as they cannot reach the site of viral reactivation 1
• Sunscreen application may help prevent recurrent HSL induced by UV light exposure 6
• After 1 year of continuous suppressive therapy, consider discontinuation to assess the patient's rate of recurrent episodes, as frequency decreases over time in many patients 1