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

Treatment of Fever Blisters (Herpes Labialis)

Oral antiviral medications are the most effective treatment for fever blisters, with valacyclovir 2g twice daily for 1 day being the recommended first-line therapy for adults. 1, 2

First-Line Treatment Options

Oral Antiviral Medications

• Valacyclovir: 2g twice daily for 1 day (most effective short-course regimen) 1, 2
• Famciclovir: 1500mg as a single dose or 750mg twice daily for 1 day 1
• Acyclovir: 400mg five times daily for 5 days (less convenient dosing) 1, 3

Timing of Treatment

• Treatment should be initiated as early as possible, ideally during the prodromal phase (tingling, burning, itching) before lesions appear 1
• The efficacy of valacyclovir initiated after the development of clinical signs (papule, vesicle, or ulcer) has not been established 2

Topical Treatment Options

Topical Antivirals

• Docosanol 10% cream (Abreva): Apply 5 times daily until healed 4
  • FDA-approved for over-the-counter use 5
  • Modest efficacy compared to oral antivirals 6, 7
  • Works through viral fusion inhibition mechanism 5

Treatment Considerations

• Topical antivirals are less effective than systemic therapy and are not recommended as first-line treatment 3
• Topical treatments may be appropriate for mild cases or when oral medications cannot be used 8

Management of Lesions

Blister Care

• If intact blisters are present, they can be gently pierced at the base with a sterile needle to drain fluid while keeping the roof intact as a biological dressing 1
• Apply bland emollient such as petroleum jelly to support barrier function and encourage healing 1
• Monitor for signs of secondary bacterial infection 1

Special Populations

Children and Adolescents

• Valacyclovir is indicated for cold sores in patients ≥12 years of age 2
• For children <12 years, consult a physician 4

Prevention of Recurrence and Transmission

• Avoid triggers (UV exposure, stress, fatigue) 8
• Prevent transmission through avoiding direct contact with lesions 8
• For frequent recurrences (>6 episodes per year), consider suppressive therapy with daily oral antivirals 1, 3

Clinical Pearls and Pitfalls

• Early treatment is crucial - efficacy decreases significantly when treatment is delayed beyond the prodromal phase 1
• Single-day high-dose regimens (valacyclovir, famciclovir) offer better compliance than multi-day treatments 1
• Topical treatments are often less effective than oral medications but may be suitable for very mild cases 3, 6
• The window of therapeutic opportunity is brief, making patient education about early self-treatment essential 1