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

Treatment of Fever Blisters (Herpes Simplex Labialis)

Oral antiviral therapy is the most effective treatment for fever blisters (herpes labialis) and should be initiated at the earliest symptom to achieve maximum benefit. 1

Understanding Fever Blisters

Fever blisters, also known as cold sores or herpes labialis, are caused by herpes simplex virus type 1 (HSV-1). They typically progress through several stages:

1. Prodrome: Itching, burning, or tingling sensation
2. Erythema and papule formation
3. Vesicle (blister) development
4. Pustulation
5. Ulceration
6. Scabbing and healing

Peak viral replication occurs within the first 24 hours after lesion onset, making early intervention critical for treatment success 1.

Treatment Algorithm

First-Line Treatment

• Oral antiviral therapy - Start at the earliest symptom (tingling, itching, burning) 2
  • Valacyclovir: 2 grams twice daily for 1 day (doses taken 12 hours apart) 2
  • Alternative options:
    • Famciclovir: Short-course regimen
    • Aciclovir: 400 mg five times daily for 5 days

For Mild Cases or When Oral Therapy Is Not Available

• Topical antiviral agents - Apply 5 times daily for up to 5 days 1
  • Provides small clinical benefit by reducing symptom duration
  • Less effective than oral therapy

For Blisters That Have Already Formed

1. Gently cleanse blister with antimicrobial solution
2. Pierce blister at base with sterile needle (bevel facing up)
3. Apply gentle pressure with sterile gauze to facilitate drainage
4. Do not remove the blister roof (acts as biological dressing)
5. Cleanse again with antimicrobial solution after drainage
6. Apply non-adherent dressing if needed 1

Special Considerations

Pain Management

• Apply topical anesthetics for pain relief
• Consider oral analgesics for more severe pain
• Offer analgesia prior to blister care procedures 1

Prevention Strategies

• Apply sunscreen to prevent UV-induced recurrences 3
• For frequent recurrences (>6 episodes per year), consider chronic suppressive therapy with oral antivirals 1

Important Timing Considerations

• Critical window: Treatment must be initiated during the prodromal phase or within the first few hours of symptoms
• The efficacy of valacyclovir initiated after clinical signs have developed (papule, vesicle, or ulcer) has not been established 2

Common Pitfalls to Avoid

1. Delayed treatment: Starting treatment after vesicles have formed significantly reduces efficacy
2. Inadequate dosing: Short-course, high-dose therapy is more effective than longer courses with lower doses 1
3. Removing blister roof: This increases pain and risk of infection 1
4. Using topical antivirals for prevention: Topical agents are not effective for prophylaxis 4
5. Expecting complete prevention: Even with optimal treatment, the goal is to reduce duration and severity, not completely abort the outbreak

Evidence Quality and Considerations

The evidence for oral antiviral therapy is stronger than for topical treatments. Short-course, high-dose valacyclovir offers greater convenience and potentially better adherence compared to multiple-day regimens 1. The FDA specifically notes that valacyclovir should be initiated at the earliest symptom of a cold sore for maximum effectiveness 2.

For patients with frequent recurrences (>6 per year), chronic suppressive therapy with oral antivirals may be beneficial, though this approach should be reserved for those with significant disease burden 3.