What is the treatment for a cold sore (herpes simplex virus) inside the mouth?

Treatment of Cold Sores Inside the Mouth

Oral antiviral medications are the first-line treatment for cold sores (herpes simplex virus) inside the mouth, with valacyclovir 2g twice daily for 1 day being the most effective regimen based on the most recent evidence. 1, 2

First-Line Treatment Options

Oral Antiviral Medications

• Valacyclovir (preferred):

  • 2g twice daily for 1 day 2, 3
  • Alternative: 1g twice daily for 1 day 1
  • Benefits: Better bioavailability than acyclovir, convenient dosing, reduces healing time by approximately 1 day 3

• Famciclovir:

  • 1500mg as a single dose or 750mg twice daily for 1 day 1
  • Well-tolerated with minimal adverse events (headache, nausea <10%) 1

• Acyclovir:

  • 400mg orally three times daily for 7-10 days 1
  • 200mg orally five times daily for 7-10 days 1
  • Less convenient dosing schedule compared to newer antivirals

Treatment Algorithm

1. Start treatment immediately at the first sign of symptoms (prodrome phase)

   • Early treatment is critical as peak viral titers occur within the first 24 hours 1
   • Treatment initiated during the prodromal phase may prevent lesion development 1

2. Choose the appropriate antiviral based on:

   • Convenience: Valacyclovir offers the simplest dosing (1-day regimen)
   • Patient factors: Consider renal function when prescribing antivirals
   • Previous response: If patient has responded well to a specific antiviral previously

3. For severe or recurrent cases:

   • Consider suppressive therapy with daily antivirals if episodes are frequent 1
   • Valacyclovir 500mg daily has shown efficacy for suppression 1, 4

Special Considerations

Inside the Mouth vs. Lip Lesions

• Intraoral herpes lesions may be more painful and interfere with eating/drinking
• Oral antivirals are more effective than topical treatments for intraoral lesions 1
• Topical treatments are generally ineffective for lesions inside the mouth due to poor retention and saliva dilution

Common Pitfalls to Avoid

1. Delayed treatment

   • Starting treatment after vesicle formation significantly reduces efficacy 1, 3
   • The therapeutic window is brief; patients should be educated to start treatment immediately

2. Confusing aphthous ulcers (canker sores) with herpes lesions

   • Antivirals are ineffective for aphthous stomatitis 5
   • Herpes typically presents with grouped vesicles that rupture and coalesce
   • Aphthous ulcers are usually round/oval with a white-yellow center and red halo

3. Relying solely on topical treatments

   • Topical antivirals have limited efficacy, especially for intraoral lesions 1
   • Oral antivirals provide superior systemic distribution to the affected site

Supportive Measures

• Pain management: Over-the-counter pain relievers (acetaminophen, ibuprofen)
• Avoid spicy, acidic, or salty foods that may irritate lesions
• Maintain good oral hygiene but avoid alcohol-based mouthwashes
• Stay hydrated and use cold beverages/foods to soothe discomfort

Prevention Strategies

• Identify and avoid triggers (stress, sunlight, illness)
• For frequent recurrences (>6 episodes/year), consider suppressive therapy 1, 4
• Valacyclovir or famciclovir have demonstrated efficacy for long-term suppression 4

The evidence strongly supports early treatment with oral antivirals, particularly high-dose, short-duration valacyclovir therapy, as the most effective approach for treating cold sores inside the mouth 1, 2, 3.