Valacyclovir
Valacyclovir (valaciclovir) is an oral prodrug of acyclovir used for several herpesvirus infections. It can shorten or suppress outbreaks but does not eradicate latent herpes infection from the body.
At a glance
Quick facts
- Drug class
- Antiviral nucleoside analogue prodrug
- Main uses
- Herpes zoster (shingles), genital herpes treatment/suppression and herpes labialis; varicella indications vary by age and market
- Route
- Oral
- WHO ATC
- J05AB11
- Key safety
- Kidney injury and neurotoxicity can occur when exposure is excessive, especially with renal impairment or dehydration; rare thrombotic microangiopathy has occurred in severely immunocompromised patients at high doses.
- Monitoring
- Kidney function and dose adjustment when indicated, hydration, neurologic symptoms and treatment timing relative to outbreak onset.
Names & terminology
How this medicine may be named or searched
- Canonical page name
- Valacyclovir
- INN / generic name
- Valaciclovir
- Aliases / salts
- valacyclovir · valaciclovir · valacyclovir hydrochloride
- Russian support entity
- valaciclovir.ru — entity relationship only, not a clinical source
Structured drug profile
Drug profile
What is Valacyclovir?
Valacyclovir (valaciclovir) is an oral prodrug of acyclovir used for several herpesvirus infections. It can shorten or suppress outbreaks but does not eradicate latent herpes infection from the body.
What is Valacyclovir used for?
Herpes zoster (shingles), genital herpes treatment/suppression and herpes labialis; varicella indications vary by age and market. The exact approved indication depends on the product, route and country. [1]
How it works
Rapidly converted to acyclovir, which inhibits viral DNA polymerase after phosphorylation in herpesvirus-infected cells.
Forms and formulations
Tablets. Different formulations may have different indications, strengths, excipients and instructions and should not be assumed interchangeable.
Country / market layer
Availability and formulations by market
Brand names, strengths, prescription status and approved uses vary by jurisdiction. Check the exact national product record before relying on a formulation.
Availability depends on the active ingredient, route and formulation; not every medicine in this reference has a current UK product.
U.S. authorization and formulation availability may differ substantially from Europe and other markets.
How it is used
Start and continue the regimen exactly as directed for the specific infection. Several indications are time-sensitive, so early initiation after symptoms begin can matter. Renal impairment can require dose reduction.
For prescription treatment, use the patient-specific regimen rather than copying a dose from another person or another formulation.
Side effects
Headache, nausea and abdominal symptoms are common. Confusion, hallucinations, tremor, seizures or kidney injury are uncommon but more likely when concentrations become excessive.
Important warnings and monitoring
Seek urgent review for markedly reduced urine output, severe confusion, seizures or unusual bruising. Older adults and people with kidney impairment need particular attention to dose and hydration.
Monitoring context: Kidney function and dose adjustment when indicated, hydration, neurologic symptoms and treatment timing relative to outbreak onset.
Interactions
Other nephrotoxic medicines can increase kidney risk. Because valacyclovir is cleared renally after conversion to acyclovir, medicines affecting renal tubular handling may alter exposure.
Pregnancy and breastfeeding
Available experience is generally reassuring, and treatment may be clinically important in pregnancy for herpes management. Decisions should be indication-specific and coordinated with obstetric care when relevant.
Overdose and accidental extra doses
Large overdoses or repeated excessive dosing can produce kidney failure and neurologic toxicity. Significant excess dosing needs urgent assessment.
Practical clinical context
The most important distinction is between the medicine entity and a specific marketed product. Strength, salt, route, modified-release design, age authorization and prescription status can change between products. When safety or dosing decisions matter, use the exact package leaflet, prescribing information or national regulator record for the product actually being used.
This page deliberately separates general evidence from the project’s Russian-language support site valaciclovir.ru; that site identifies the cross-language entity but is not treated as an authority for clinical claims.
Common questions
Frequently asked questions
Yes. Valacyclovir is the U.S. spelling; valaciclovir is the INN spelling used in many other countries.
No. It treats or suppresses outbreaks but does not eliminate latent herpesvirus infection.
The active drug is cleared through the kidneys, and excessive exposure can cause kidney and neurologic toxicity.
Many regimens work best when started early after symptoms begin, according to the product-specific instructions.
Suppressive therapy can reduce transmission risk but does not eliminate it, so safer-sex measures remain important.
Sources
Clinical statements in this reference are based on named public-health, regulatory or guideline sources. Product-specific labeling remains authoritative for exact indications, dosing and contraindications.
- 1. MedlinePlus. Valacyclovir Drug Information, revised May 2026. Source ↗
- 2. DailyMed. Valacyclovir product labeling search. Source ↗
This medicine reference is evidence-based and is awaiting clinician review. It is not a substitute for personalized medical advice.