How should herpes labialis be treated?

Treatment of Fever Blisters (Herpes Labialis)

For episodic treatment of cold sores, start valacyclovir 2g twice daily for 1 day (doses separated by 12 hours) at the first sign of symptoms—this high-dose, short-course regimen reduces episode duration by approximately one day and offers superior convenience compared to traditional longer courses. 1

First-Line Oral Antiviral Options

Oral antiviral therapy is markedly superior to topical treatments and must be initiated during the prodromal phase (tingling, burning, itching) or within 24 hours of lesion onset to achieve optimal benefit. 1 Peak viral titers occur in the first 24 hours after lesion appearance, making early viral replication blockade essential. 1 Starting treatment after this window markedly diminishes clinical efficacy. 1

Recommended Episodic Regimens (in order of convenience):

• Valacyclovir 2g orally twice daily for 1 day (12 hours apart)—first-line choice with highest convenience and proven efficacy 1
• Famciclovir 1500mg as a single oral dose—equally effective alternative with single-day dosing 1
• Acyclovir 400mg orally five times daily for 5 days—effective but requires more frequent dosing, which may reduce adherence 1

All three regimens are generally well-tolerated with minimal adverse events. 1 Common side effects include headache (<10%), nausea (<4%), and diarrhea, typically mild to moderate in intensity. 1

When to Consider Suppressive Therapy

Patients experiencing six or more recurrences per year should be offered daily suppressive therapy, which reduces recurrence frequency by ≥75%. 1

Suppressive Therapy Options:

• Valacyclovir 500mg once daily (can increase to 1000mg once daily for very frequent recurrences) 1
• Famciclovir 250mg twice daily 1
• Acyclovir 400mg twice daily 1

Safety and efficacy have been documented for acyclovir for up to 6 years and for valacyclovir/famciclovir for 1 year of continuous use. 1 After 1 year of suppressive therapy, consider discontinuation to reassess recurrence frequency, as it decreases over time in many patients. 1

Additional Indications for Suppressive Therapy:

• Particularly severe, frequent, or complicated disease 1
• Significant psychological distress from recurrences 1

Critical Timing and Patient Counseling

Provide patients with a prescription to keep on hand so treatment can be initiated immediately at first symptoms—patient-initiated therapy at prodromal symptoms may even prevent lesion development in some cases. 1

Trigger Avoidance:

• Apply sunscreen (SPF ≥15) or zinc oxide before sun exposure—UV light is a major trigger and prevention can effectively reduce UV-induced outbreaks 1
• Counsel patients to identify and avoid personal triggers including fever, psychological stress, and menstruation 1

Contagiousness and Transmission Prevention

Patients remain contagious until all lesions are fully crusted—this is the clinical endpoint indicating substantial reduction in transmission risk. 1 Even with optimal antiviral therapy, viral shedding persists for approximately 6.4 days (compared to 8.1 days without treatment). 1

Transmission Prevention Measures:

• Avoid direct skin-to-skin contact (kissing) with the affected area until lesions are completely crusted 1
• Do not share towels, utensils, lip balm, or other objects that may contact the oral region during active outbreaks 1
• Asymptomatic viral shedding can occur even without visible lesions, so partners should be informed that zero transmission risk does not exist even after complete healing 1

Special Populations

Immunocompromised Patients:

Episodes are typically longer and more severe, potentially involving the oral cavity or extending across the face. 1 These patients may require:

• Higher doses or longer treatment durations 1
• Acyclovir resistance rates are substantially higher (7% versus <0.5% in immunocompetent hosts) 1
• For confirmed acyclovir-resistant HSV, switch to foscarnet 40mg/kg IV three times daily 1

Elderly Patients (≥80 years):

• Evaluate renal function (creatinine clearance) before initiating any oral antiviral to allow appropriate dose adjustment and avoid drug accumulation and neurotoxicity 1

Severe Gingivostomatitis Requiring Hospitalization:

• Acyclovir 5-10mg/kg IV every 8 hours until lesions begin to regress, then switch to oral therapy and continue until complete healing 1

Common Pitfalls to Avoid

• Do not rely on topical antivirals as primary therapy—they provide only modest clinical benefit and are substantially less effective than oral therapy 1, 2
• Do not use topical antivirals for suppressive therapy—they cannot reach the site of viral reactivation 1
• Do not delay treatment beyond 24 hours—efficacy decreases significantly when treatment is initiated after lesions have fully developed 1
• Failing to consider suppressive therapy in patients with ≥6 recurrences per year who could significantly benefit 1
• Not discussing trigger avoidance (UV light, stress, fever) even while on suppressive therapy 1

Laboratory Testing

Routine laboratory confirmation is not required in immunocompetent adults with typical recurrent cold sores (grouped vesicles or ulcers on the lip/perioral skin). 1 Laboratory testing should be considered for lesions that are atypical, severe, or non-healing. 1