Duration of Acyclovir Therapy for Herpes Labialis
For episodic treatment of herpes labialis (cold sores), acyclovir should be administered at 400 mg five times daily for 5 days, initiated within 1 hour of the first sign or symptom of recurrence. 1, 2
Standard Treatment Duration
The established treatment duration is 5 days for oral acyclovir 400 mg five times daily, based on clinical trial evidence demonstrating efficacy in reducing viral shedding and hastening lesion resolution 1, 2
Treatment must be initiated as early as possible—ideally during the prodromal phase or within the first hour of symptom onset—to achieve maximum benefit 2
For patients who start treatment during the prodrome or erythema stage, acyclovir reduces mean duration of pain by 36% and mean healing time to loss of crust by 27% 2
Alternative Dosing Regimens
While the question asks specifically about acyclovir, it's important to note more convenient alternatives:
Valacyclovir 2g twice daily for 1 day offers superior convenience and is now considered first-line therapy, reducing median episode duration by 1.0 day compared to placebo 3
Famciclovir 1500mg as a single dose is equally effective, significantly reducing healing time of primary lesions 3
These short-course, high-dose regimens provide greater convenience, cost benefits, and improved patient adherence compared to the traditional 5-day acyclovir course 3
Topical Acyclovir Considerations
Topical acyclovir cream (5%) applied five times daily for 4 days reduces episode duration by approximately 0.5 days but is substantially less effective than oral therapy 4
Topical formulations provide only modest clinical benefit and should not be relied upon as primary therapy 3
The limited efficacy of topical acyclovir results from inadequate penetration to the basal epidermis where viral replication occurs 5
Suppressive Therapy Duration
For patients with frequent recurrences (≥6 episodes per year):
Acyclovir 400 mg twice daily can be used for continuous suppressive therapy, with documented safety and efficacy for up to 6 years 3
After 1 year of continuous suppressive therapy, consider discontinuation to reassess recurrence frequency, as episodes often decrease over time 3
Suppressive therapy reduces recurrence frequency by ≥75% among patients with frequent outbreaks 3
Critical Timing Considerations
Peak viral titers occur within the first 24 hours after lesion onset, making early intervention essential for blocking viral replication 3
Efficacy decreases significantly when treatment is initiated after lesions have fully developed into vesicles or ulcers 3
Patient-initiated episodic therapy at first symptoms may even prevent lesion development in some cases 3
Common Pitfalls to Avoid
Starting treatment too late after lesions have progressed beyond the erythema stage significantly reduces efficacy 3, 2
Using topical acyclovir as primary therapy when oral antivirals are more effective 3
Not considering short-course, high-dose alternatives (valacyclovir or famciclovir) that improve adherence and convenience 3
Failing to counsel patients on identifying personal triggers (UV exposure, stress, fever) to enable earlier self-initiated treatment 3