Valtrex (valacyclovir)

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

Do I need a prescription for Valtrex (valacyclovir)?

Yes

What are the uses for Valtrex (valacyclovir)?

What are the side effects of Valtrex (valacyclovir)?

The side effect profile of Valtrex is similar to that of acyclovir (Zovirax).

Common side effects are:

Other important side effects are:

More serious side effects include central nervous system side effects which are more likely to happen in the elderly such as:

What is the dosage for Valtrex (valacyclovir)?

  • Valtrex may be taken with or without food. Dosages need to be reduced in patients with kidney disease.
  • For the treatment of herpes zoster (shingles), the usual dose is 1 gm. three times a day for 7 days. Treatment should begin at the first symptom and is most effective if started within 48 hours of the onset of rash. The dose for chickenpox is 20 mg/kg 3 times daily for 5 days (maximum dose is 1000 mg 3 times daily) and treatment should start at the earliest sign or symptom.
  • For the treatment of an initial episode of genital herpes, the usual dose is 1 gram (1000 mg) twice daily for 10 days. For the treatment of recurrent genital herpes, the usual dose is 500 mg twice daily for 3 days. For best results, treatment should be initiated within 12 hours of the start of symptoms.
  • The dose for cold sores is 2000 mg (2 grams) every 12 hours for 1 day.

Which drugs or supplements interact with Valtrex (valacyclovir)?

  • Probenecid (Benemid) and cimetidine (Tagamet) may reduce the kidney's clearance of Valtrex, leading to higher concentrations in the blood. This may lead to side effects of Valtrex.

Is Valtrex (valacyclovir) safe to use during pregnancy or while breastfeeding?

  • Valtrex showed no effects on the fetus in animal studies; however, there has been no adequate evaluation of valacyclovir or (acyclovir) in pregnant women. The incidence of birth defects in women taking acyclovir is about the same as in the general population. Valtrex should only be used during pregnancy when the benefits to the mother outweigh risks to the fetus.
  • It is not known whether Valtrex is excreted into breast milk. It is known, however, that among women taking acyclovir, concentrations of acyclovir in breast milk are about four times higher than in the mother's blood. The safety of valacyclovir in breastfeeding infants has not been established. Methods other than breastfeeding should be considered if valacyclovir must be taken while nursing.

What else should I know about Valtrex (valacyclovir)?

What preparations of Valtrex (valacyclovir) are available?
  • Tablets : 500, 1000 mg
How should I keep Valtrex (valacyclovir) stored?
  • Valtrex should be kept between 2 C and 30 C (36 F and 86 F).
How does Valtrex (valacyclovir) work?
  • Valtrex belongs to a class of drugs called nucleoside analogs that mimic one of the building blocks of DNA. It stops the spread of herpes virus in the body by preventing the replication of viral DNA that is necessary for viruses to multiply. Other drugs in the same class include acyclovir (Zovirax) and famciclovir (Famvir). Valacyclovir is actually a "prodrug," in that it is not active itself. Rather, it is converted to acyclovirin the body, and it is the acyclovir that is active against the viruses. (Acyclovir itself is available as a topical, oral and intravenous medication.) Valacyclovir, therefore, is active against the same viruses as acyclovir, but valacyclovir has a longer duration of action than acyclovir, and, therefore, can be taken fewer times each day.
When was Valtrex (valacyclovir) approved by the FDA?
  • Valacyclovir was approved for use by the FDA in 1995.

Reference: FDA Prescribing Information

Last Editorial Review: 11/23/2016

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See more info: valacyclovir on RxList
Reviewed on 11/23/2016
References
Reference: FDA Prescribing Information

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