Famciclovir Dosing for Suppressive Therapy of Cold Sores
Famciclovir is not approved or recommended for suppressive therapy of herpes labialis (cold sores) in the United States or most countries. 1
Current Approved Indications
Famciclovir has received approval only for episodic treatment of herpes labialis, not suppressive therapy:
- Single-dose regimen: 1500 mg as a single dose 1, 2
- Twice-daily regimen: 750 mg twice daily for 1 day 1
Both regimens demonstrated reduced median healing times (4.0-4.4 days) compared to placebo (6.2 days) when initiated early in the prodromal phase. 1
Why Suppressive Therapy Is Not Standard for Cold Sores
The evidence base focuses exclusively on episodic treatment for herpes labialis rather than chronic suppression. 1 This differs fundamentally from genital herpes, where suppressive therapy is well-established.
Approved Suppressive Dosing (For Genital Herpes Only)
If you are considering famciclovir for suppressive therapy, note that approval exists only for recurrent genital herpes:
- US approval: 250 mg twice daily for suppression of recurrent genital herpes 1
- Australian approval: Different episodic regimen (500 mg single dose followed by three 250 mg doses) 1
The suppressive dose of 250 mg twice daily has been studied for genital herpes with demonstrated efficacy in extending time to recurrence. 3
Clinical Pitfalls
- Do not extrapolate genital herpes dosing to herpes labialis: The regulatory approvals, disease patterns, and treatment goals differ substantially between these conditions 1
- Resistance remains low: Despite 20 years of antiviral use for herpes labialis, HSV-1 resistance rates remain <0.5% in immunocompetent hosts 1
- Timing is critical for episodic therapy: Treatment must be initiated during the prodromal phase for maximum efficacy 1
Alternative Consideration
For patients requiring suppression of frequent herpes labialis recurrences, valacyclovir or acyclovir would be more appropriate choices, as these have established suppressive regimens with documented safety for extended use (acyclovir up to 6 years, valacyclovir up to 1 year). 4