What is the recommended dose of Valacyclovir (Valtrex) for adults with herpes simplex or herpes zoster?

Valacyclovir Dosing for Herpes Simplex and Herpes Zoster

For herpes simplex, use 500 mg twice daily for recurrent episodes (3-5 days) or 1 gram once daily for suppression; for herpes zoster, use 1 gram three times daily for 7 days, initiated within 72 hours of rash onset. 1

Herpes Simplex Virus Dosing

Initial Genital Herpes Episode

• 1 gram twice daily for 10 days is the FDA-approved regimen for first episodes 1
• Treatment is most effective when started within 48 hours of symptom onset 1

Recurrent Genital Herpes Episodes

• 500 mg twice daily for 3 days for episodic treatment 1
• Initiate at the first sign or symptom of recurrence 1
• Alternative regimens include 500 mg twice daily for 5 days, which is equally effective 2

Suppressive Therapy for Recurrent Genital Herpes

• 1 gram once daily for patients with normal immune function 1
• 500 mg once daily is acceptable for patients with 9 or fewer recurrences per year 1, 3
• Avoid 500 mg once daily in patients with ≥10 recurrences per year, as this dose is less effective in this population; use 1 gram once daily instead 3
• For HIV-infected patients with CD4+ count ≥100 cells/mm³, use 500 mg twice daily 1, 3
• Suppressive therapy reduces recurrences by ≥75% and has documented safety for up to 1 year 3

Orofacial Herpes (Cold Sores)

• 2 grams twice daily for 1 day (12 hours apart) 1
• Initiate at earliest symptom (tingling, itching, burning) 1

Ophthalmic HSV

• 500 mg two or three times daily for HSV blepharoconjunctivitis 4
• Oral antivirals alone may be inadequate; addition of topical antiviral treatment is often necessary 4

Herpes Zoster (Shingles) Dosing

Standard Immunocompetent Adults

• 1 gram three times daily for 7 days 1, 5
• Must initiate within 72 hours of rash onset for optimal efficacy in reducing acute pain and preventing postherpetic neuralgia 5
• Most effective when started within 48 hours 1
• Continue treatment until all lesions have completely scabbed, not just for an arbitrary 7-day period 5

Alternative Dosing for Herpes Zoster

• 1.5 grams twice daily for 7 days has been shown safe and effective in immunocompetent adults, potentially improving compliance over three-times-daily dosing 6
• For persistent or recalcitrant ophthalmic herpes zoster, 1000 mg every 8 hours for 7 days may be used 7

Varicella Zoster Virus Conjunctivitis

• 1000 mg every 8 hours for 7 days for persistent or recalcitrant acute/subacute disease in immunocompetent patients 4
• Immunocompromised patients may need more aggressive treatment 4

Special Populations

Immunocompromised Patients

• Higher doses or extended duration may be necessary 5, 7
• For severe, disseminated, or invasive herpes zoster, switch to intravenous acyclovir 10 mg/kg every 8 hours 5
• Avoid valacyclovir 8 grams per day in immunocompromised patients due to risk of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome 4, 3, 8
• Immunocompromised patients with herpes zoster may require treatment extension well beyond 7-10 days as lesions develop over 7-14 days and heal more slowly 5

HIV-Infected Patients

• For genital herpes suppression with CD4+ ≥100 cells/mm³: 500 mg twice daily 1, 3
• Higher doses (up to 1 gram three times daily) may be needed for herpes zoster 4

Renal Impairment

• Dose adjustment is mandatory to prevent acute renal failure 1, 4
• For CrCl 30-49 mL/min: no reduction needed for most indications 3
• For CrCl <30 mL/min: 500 mg every 24-48 hours 4
• For hemodialysis: 500 mg after each dialysis 4

Pregnancy

• Safety not fully established, but current registry findings show no increased risk of major birth defects compared to general population 4, 3
• First clinical episode during pregnancy may be treated with oral valacyclovir 4

Critical Clinical Considerations

Treatment Failure and Resistance

• If lesions persist despite appropriate therapy, suspect acyclovir resistance 3, 5
• All acyclovir-resistant strains are also resistant to valacyclovir 4, 3
• For proven or suspected resistance: IV foscarnet 40 mg/kg every 8 hours until clinical resolution 4, 5

Monitoring

• No laboratory monitoring needed for immunocompetent patients on suppressive therapy unless substantial renal impairment exists 3
• For IV acyclovir in immunocompromised patients, monitor renal function at initiation and once or twice weekly 5
• Assess for thrombotic thrombocytopenic purpura/hemolytic uremic syndrome in immunocompromised patients receiving high-dose therapy 5

Common Pitfalls to Avoid

• Do not use topical antivirals alone for herpes zoster—they are substantially less effective than systemic therapy 5
• Do not stop treatment at exactly 7 days if lesions are still forming or have not completely scabbed 5
• Do not use short-course genital herpes regimens (3-5 days) for varicella zoster virus infections—they are inadequate 5
• Do not delay treatment beyond 72 hours of rash onset for herpes zoster, as efficacy diminishes significantly 5, 1

After 1 Year of Suppressive Therapy

• Consider discussing discontinuation to reassess recurrence frequency, as recurrences may decrease over time 3