Valacyclovir (Valtrex) Dosing for Herpes Outbreaks
For oral herpes (cold sores), the recommended dose of valacyclovir is 2 grams twice daily for 1 day, taken 12 hours apart. 1, 2
Dosing Recommendations by Type of Herpes Outbreak
Oral Herpes (Cold Sores/Herpes Labialis)
- 2 grams twice daily for 1 day, taken 12 hours apart 1, 2
- Therapy should be initiated at the earliest symptom of a cold sore (e.g., tingling, itching, or burning) 1
- This short-course therapy has demonstrated significant reduction in episode duration compared to placebo 2
Genital Herpes
- Initial episode: 1 gram twice daily for 10 days 1
- Recurrent episodes: 500 mg twice daily for 5 days 1, 3
- Suppressive therapy: 1 gram once daily for patients with normal immune function 1
- For patients with 9 or fewer recurrences per year, an alternative suppressive dose is 500 mg once daily 1
- For HIV-infected patients with CD4+ count ≥100 cells/mm³, the recommended suppressive dose is 500 mg twice daily 1
Timing of Treatment Initiation
- Treatment should be initiated during the prodromal phase (when experiencing tingling, itching, or burning) or within 1 day after onset of lesions for maximum effectiveness 3
- Early initiation of therapy during the prodromal phase may potentially prevent lesion development 2
- Valacyclovir therapy is most effective when started at the earliest sign or symptom of an outbreak 1
Efficacy Considerations
- Valacyclovir has enhanced absorption after oral administration compared to acyclovir 3
- It can reduce the duration of symptoms, decrease pain associated with lesions, and accelerate healing time 3, 2
- For oral herpes, valacyclovir treatment has shown a shorter median duration of episodes (4.0-5.0 days) compared to placebo 3, 2
- For genital herpes, valacyclovir 500 mg twice daily for 5 days has been shown to be as effective as longer treatment regimens 4, 5
Special Considerations
- For immunocompromised patients, standard dosing is typically used, but these patients should be monitored more closely 2
- Valacyclovir is generally well-tolerated with common adverse events including headache, nausea, and gastrointestinal complaints 2, 6
- No laboratory monitoring is needed in patients receiving therapy unless they have substantial renal impairment 7
- Valacyclovir may be given without regard to meals 1
Common Pitfalls and Caveats
- Valacyclovir 500 mg once daily appears less effective than other valacyclovir dosing regimens in patients who have very frequent recurrences (≥10 episodes per year) 4, 7
- Suppressive treatment reduces but does not eliminate asymptomatic viral shedding 7
- After 1 year of continuous suppressive therapy, discontinuation should be considered to assess the patient's rate of recurrent episodes, as recurrence frequency often decreases over time 4, 7
- High-dose valacyclovir (8 g/day) has been associated with thrombotic thrombocytopenic purpura/hemolytic uremic syndrome, but this has not been reported at doses used for herpes suppression 7, 8