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

Treatment of Fever Blisters (Herpes Simplex Labialis)

Oral antiviral medications are the standard of care for treating fever blisters, with valacyclovir being the preferred option due to its superior bioavailability and simpler dosing regimen. 1

First-Line Treatment Options

Oral Antiviral Medications

• Valacyclovir: 1g twice daily for 7-10 days 1

  • Better bioavailability than acyclovir
  • Requires less frequent dosing (twice daily)
  • FDA-approved for cold sores in patients ≥12 years 2
  • Most effective when started within 24-48 hours of symptom onset

• Acyclovir: 200mg 5 times daily for 5-7 days 1

  • Alternative option if valacyclovir is unavailable
  • Can also be used as suppressive therapy at 400mg twice daily 1

• Famciclovir: 250mg three times daily for 5-7 days 1

  • Similar efficacy to valacyclovir but may be slightly less effective for suppression 3

Timing of Treatment

• Treatment should be initiated as early as possible, ideally:
  • Within 24-48 hours of first symptoms
  • At the first sign of prodrome (tingling, burning sensation)
  • Efficacy decreases significantly if started after vesicle formation 1, 2

Special Patient Populations

Immunocompromised Patients

• Higher doses and longer duration of treatment recommended:
  • Acyclovir 400mg five times daily for 7-10 days 1
  • Consider IV acyclovir for severe cases 1

Pregnant Patients

• Acyclovir 400mg orally three times daily for 5-7 days
• Acyclovir has established safety profile in pregnancy (FDA category B) 1

Topical Treatments

• Less effective than oral medications but may provide modest benefit:
  • Penciclovir cream (Denavir): Apply every 2 hours while awake for 4 days 4
    • Reduces lesion duration by approximately half a day compared to placebo
    • Also reduces duration of lesion pain 4
  • Acyclovir 5% cream: Limited efficacy when used alone 5, 6

Prevention Strategies

• For frequent recurrences (≥6 episodes per year), consider suppressive therapy:

  • Valacyclovir 500mg daily 1
  • Acyclovir 400mg twice daily 1

• Additional preventive measures:

  • Use sunscreen (SPF 15 or higher) to prevent UV-triggered recurrences 1, 5
  • Avoid known triggers (stress, fatigue, immunosuppression) 1
  • Keep affected area clean and dry to prevent secondary infection 1

Treatment Monitoring

• Improvement should be seen within 7-10 days of starting treatment 1
• If lesions do not begin to resolve within this timeframe, consider:
  • Treatment failure
  • Possible antiviral resistance
  • Need for alternative treatments 1

Common Pitfalls to Avoid

1. Delayed treatment initiation: Starting treatment after vesicle formation significantly reduces efficacy
2. Inadequate dosing: Using too low a dose or stopping treatment prematurely
3. Relying solely on topical treatments: Oral antivirals are substantially more effective
4. Failing to consider suppressive therapy for patients with frequent recurrences
5. Not addressing underlying triggers that may precipitate outbreaks

Remember that while treatment can reduce the duration and severity of symptoms, it does not eliminate the virus or prevent future recurrences completely 7.