Author: Dr. Elena M. Petrova, MD
Specialty: Infectious Diseases & Viral Infections
Last updated: November 18, 2025
What is Valtrex (Valacyclovir) Used For?
Valtrex (valacyclovir hydrochloride) is a nucleoside analogue DNA polymerase inhibitor and a prodrug of acyclovir. It is FDA-approved for:
- Treatment of herpes zoster (shingles) in immunocompetent adults
- Treatment of initial and recurrent genital herpes in immunocompetent adults
- Suppressive therapy of recurrent genital herpes
- Treatment of herpes labialis (cold sores)
- Treatment of chickenpox (varicella) in immunocompetent children ≥2 years
- Reduction of transmission risk of genital herpes with suppressive therapy
Dosing Regimens and Treatment Schemes
| Indication | Dosage | Duration | Notes |
|---|---|---|---|
| Herpes Zoster (Shingles) | 1 g three times daily | 7 days | Start within 72 hours of rash onset |
| Initial Genital Herpes | 1 g twice daily | 10 days | Or 500 mg twice daily for 7–10 days |
| Recurrent Genital Herpes | 500 mg twice daily | 3 days | Start at first sign/symptom |
| Suppressive Therapy (≥6 outbreaks/year) | 1 g once daily or 500 mg once daily (if <10 outbreaks/year) |
Continuous | Reassess annually |
| Cold Sores (Herpes Labialis) | 2 g twice daily (12 hours apart) | 1 day | Most effective if started at prodrome |
| Chickenpox (Children ≥2 years) | 20 mg/kg three times daily (max 1 g TID) | 5 days | Start within 24 hours of rash |
Comparison with Other Antivirals
| Drug | Bioavailability | Dosing Frequency | Shingles Duration Reduction | Cost (Generic 30-day) |
|---|---|---|---|---|
| Valacyclovir (Valtrex) | 55% | 1–3 times daily | ~1.5–2 days | $20–80 |
| Acyclovir (Zovirax) | 15–20% | 5 times daily | ~1–1.5 days | $15–50 |
| Famciclovir (Famvir) | 77% | 2–3 times daily | ~1.5–2 days | $150–300 |
Official Sources & Clinical Evidence
FDA Prescribing Information: Valtrex FDA Label
EMA Summary of Product Characteristics: Valtrex EMA SmPC
Major Study (New England Journal of Medicine): PubMed – Valacyclovir and Transmission Reduction
Customer Reviews
Sarah L., 34, California ★★★★★
“Cold sores gone in 2 days with the 2g x 2 regimen. Best treatment I’ve ever used.”
“Cold sores gone in 2 days with the 2g x 2 regimen. Best treatment I’ve ever used.”
Mike T., 52, Texas ★★★★★
“Shingles pain was unbearable. Started Valtrex day 2 — rash healed in 8 days instead of weeks.”
“Shingles pain was unbearable. Started Valtrex day 2 — rash healed in 8 days instead of weeks.”
Emma R., 29, New York ★★★★☆
“On 500mg daily suppression for 2 years — zero outbreaks. Life-changing.”
“On 500mg daily suppression for 2 years — zero outbreaks. Life-changing.”
James K., 41, Florida ★★★★★
“Used for recurrent genital herpes — 3-day course works every time.”
“Used for recurrent genital herpes — 3-day course works every time.”
Lisa M., 37, Illinois ★★★★★
“Took for chickenpox in my 6-year-old — rash cleared much faster than expected.”
“Took for chickenpox in my 6-year-old — rash cleared much faster than expected.”
Frequently Asked Questions (FAQ)
Yes. Valtrex is the brand name; valacyclovir is the generic and is FDA-approved as AB-rated equivalent.
No direct interaction, but alcohol may worsen dehydration and delay healing.
Can be lifelong if outbreaks are frequent. Re-evaluate with your doctor annually.
Category B — large registry shows no increased risk. Used routinely in pregnancy when needed.
This information is for educational purposes only and does not replace professional medical advice. Always consult your healthcare provider.