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valacyclovir hydrochloride (valaciclovir (UK))

Apo-Valacyclovir, Valtrex

Pharmacologic class: Acyclic purine nucleoside analog

Therapeutic class: Antiviral

Pregnancy risk category B


Rapidly converts to acyclovir, which interferes with viral DNA synthesis and replication


Caplets: 500 mg, 1 g

Indications and dosages

Herpes zoster (shingles)

Adults: 1 g P.O. t.i.d. for 7 days. Therapy should begin at first sign or symptom of herpes zoster, within 48 hours of onset of zoster rash.

Genital herpes

Adults: For initial episode, 1 g P.O. b.i.d. for 10 days. For recurrent episodes, 500 mg P.O. b.i.d. for 3 days. For chronic suppression, 1 g P.O. daily for no more than 1 year; in patients with history of fewer than nine yearly recurrences, 500 mg P.O. daily for no more than 1 year.

To reduce risk of genital herpes in immunocompetent patients

Adults: 500 mg P.O. daily for source partner, along with counseling regarding safe sex practices

Herpes labialis

Adults: 2 g b.i.d. for 1 day taken 12 hours apart. Begin therapy at first symptom of lesion.

Dosage adjustment

• Renal impairment

Off-label uses

• Cytomegalovirus prophylaxis


• Hypersensitivity to drug, its components, or acyclovir


Use cautiously in:

• renal impairment, concurrent use of nephrotoxic drugs, inadequately hydrated patients

• elderly patients

• pregnant or breastfeeding patients

• children.


• Be aware that therapy may be ineffective if begun more than 72 hours after initial genital herpes outbreak, or more than 24 hours after symptom onset in herpes recurrence.

Adverse reactions

CNS: headache, dizziness, depression, agitation, hallucinations, confusion, encephalopathy

GI: nausea, vomiting, diarrhea, abdominal pain

GU: dysmenorrhea, acute renal failure

Hematologic: anemia, leukopenia, thrombocytopenia, hemolytic uremic syndrome/thrombotic thrombocytopenic purpura/(HUS/TTP)

Musculoskeletal: joint pain

Other: hypersensitivity reaction


Drug-drug. Cimetidine, probenecid: increased valacyclovir blood level

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase: increased levels

Patient monitoring

Monitor CBC. Stay alert for signs and symptoms of blood dyscrasias. Discontinue drug if clinical signs and symptoms and laboratory findings consistent with HUS/TTP occur.

• Assess liver and kidney function tests.

Patient teaching

• Inform patient that herpes transmission can occur even when he is asymptomatic.

• Tell patient and significant other that no cure exists for herpes. Urge them to practice safe sex.

• Inform pregnant patient of risk of neonatal herpes infection.

• Instruct pregnant patient or female of childbearing age to tell health care provider that she has herpes. After delivery, tell her to inform neonatal care providers.

Instruct patient to promptly report unusual bleeding or bruising, urinary changes, or serious adverse CNS reactions.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs and tests mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved


(val-ay-sye-kloe-veer) ,


(trade name)


Therapeutic: antivirals
Pregnancy Category: B


Treatment of herpes zoster (shingles).Treatment/suppression of genital herpes.Reduction of transmission of genital herpes.Treatment of chickenpox.Treatment of herpes labialis (cold sores).


Rapidly converted to acyclovir. Acyclovir interferes with viral DNA synthesis.

Therapeutic effects

Inhibited viral replication, decreased viral shedding, reduced time to healing of lesions.
Reduced transmission of genital herpes.


Absorption: 54% bioavailable as acyclovir after oral administration of valacyclovir.
Distribution: CSF concentrations of acyclovir are 50% of plasma concentrations. Acyclovir crosses placenta; enters breast milk.
Metabolism and Excretion: Rapidly converted to acyclovir via intestinal/hepatic metabolism.
Half-life: 2.5–3.3 hr; up to 14 hr in renal impairment (acyclovir).

Time/action profile (blood levels†)

POunknown1.5–2.5 hr8–24 hr


Contraindicated in: Hypersensitivity to valacyclovir or acyclovir.
Use Cautiously in: Renal impairment (↓ dose/↑ dosing interval recommended if CCr <50 mL/min); Obstetric / Lactation / Pediatric: Pregnancy, lactation, or children <2 yr (safety not established); Geriatric: Dose ↓ may be necessary due to ↑ risk of acute renal failure and CNS side effects.

Adverse Reactions/Side Effects

Central nervous system

  • headache (most frequent)
  • agitation
  • confusion
  • delirium
  • dizziness
  • encephalopathy
  • hallucinations
  • seizures
  • weakness


  • nausea (most frequent)
  • abdominal pain
  • anorexia
  • constipation
  • diarrhea


  • renal failure (life-threatening)
  • crystalluria


  • thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (very high doses in immunosuppressed patients) (life-threatening)


Drug-Drug interaction

Probenecid and cimetidine ↑ blood levels; significant only in renal impairment.Concurrent use of other nephrotoxic drugs ↑ risk of adverse renal effects.


Herpes Zoster
Oral (Adults) 1 g 3 times daily for 7 days.
Genital Herpes
Oral (Adults) Initial treatment—1 g twice daily for 10 days. Recurrence—500 mg twice daily for 3 days. Suppression of recurrence—1 g once daily or 500 mg once daily in patients experiencing <10 recurrences/yr. Suppression of recurrence in HIV-infected patients—500 mg q 12 hr. Reduction of transmission—500 mg once daily for source partner.
Herpes Labialis
Oral (Adults and Children ≥12 yr) 2 g then 2 g 12 hr later.
Oral (Children ≥2 yr) 20 mg/kg 3 times daily for 5 days (not to exceed 1 g 3 times daily).

Renal Impairment

Oral (Adults) CCr 30–49 mL/min—1 g q 12 hr for herpes zoster treatment, no ↓ required for treatment of genital herpes; 1 g then 1 g 12 hr later for herpes labialis. CCr 10–29 mL/min—1 g q 24 hr for initial treatment of genital herpes, 500 mg q 24 hr for treatment of recurrent episodes of genital herpes, 500 mg q 48 hr for suppression of genital herpes in patients with 9 or fewer recurrences/yr, 500 mg q 24 hr for suppression of genital herpes in patients with ≥10 recurrences/yr or HIV-infected patients, 1 g q 24 hr for treatment of herpes zoster; 500 mg then 500 mg 12 hr later for herpes labialis. CCr <10 mL/min—500 mg q 24 hr for initial treatment of genital herpes, 500 mg q 24 hr for treatment of recurrent episodes of genital herpes, 500 mg q 48 hr for suppression of genital herpes in patients with 9 or fewer recurrences/yr, 500 mg q 24 hr for suppression of genital herpes in patients with ≥10 recurrences/yr or HIV-infected patients, 500 mg q 24 hr for treatment of herpes zoster; single 500 mg dose for herpes labialis.

Availability (generic available)

Tablets: 500 mg, 1 g Cost: Generic — 500 mg $31.44 / 30, 1 g $53.34 / 30

Nursing implications

Nursing assessment

  • Assess lesions before and daily during therapy.
  • Monitor patient for signs of thrombotic thrombocytic purpura/hemolytic uremic syndrome (thrombocytopenia, microangiopathic hemolytic anemia, neurologic findings, renal dysfunction, fever). Requires prompt treatment; may be fatal.

Potential Nursing Diagnoses

Risk for impaired skin integrity (Indications)
Risk for infection (Indications,  Patient/Family Teaching)


  • high alert: Do not confuse valacyclovir with valganciclovir. Do not confuse Valtrex (valacyclovir) with Valcyte (valganciclovir).
  • Oral: May be administered without regard to meals.
  • Herpes Zoster: Implement valacyclovir therapy as soon as possible after the onset of signs or symptoms of herpes zoster; most effective if started within 48 hr of the onset of zoster rash. Efficacy of treatment started >72 hr after rash onset is unknown.
  • Genital Herpes and Herpes Labialis: Implement treatment for genital herpes as soon as possible after onset of symptoms (tingling, itching, burning).
  • Chicken Pox: Initiate therapy at the earliest sign or symptom; preferably within 24 hr of onset of rash.

Patient/Family Teaching

  • Instruct patient to take valacyclovir exactly as directed for the full course of therapy. Take missed doses as soon as remembered if not just before next dose; do not double doses. Advise patient to read the Patient Information before starting therapy.
  • Advise patient to maintain adequate hydration during therapy.
  • Advise patient to notify health care professional promptly if nervous system symptoms (aggressive behavior, unsteady movement, shaky movements, confusion, speech problems, hallucinations, seizures, coma) occur.
  • Instruct patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and consult health care professional before taking any new medications.
  • Instruct female patients to notify health care professional if pregnancy is planned or suspected, or if breast feeding.
  • Herpes Zoster: Inform patient that valacyclovir does not prevent the spread of infection to others. Precautions should be taken around others who have not had chickenpox or varicella vaccine, or are immunosuppressed, until all lesions have crusted.
  • Genital Herpes and Herpes Labialis: Inform patient that valacyclovir does not prevent the spread of herpes labialis to others. Advise patient to avoid contact with lesions while lesions or symptoms are present. Valacyclovir reduces transmission of genital herpes to others. Advise patient to practice safe sex (avoid sexual intercourse when lesions are present and wear a condom made of latex or polyurethane during sexual contact).

Evaluation/Desired Outcomes

  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with acute herpes zoster (shingles).
  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with genital herpes.
  • Decrease in frequency of outbreaks in patients with genital herpes.
  • Decrease in time to full crusting, loss of vesicles, loss of ulcers, and development of crusts in patients with herpes labialis. Decrease in transmission of genital herpes.
  • Treatment of chickenpox.
Drug Guide, © 2015 Farlex and Partners


A trademark for the drug valacyclovir hydrochloride.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


A brand name for VALACICLOVIR.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
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