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Valacyclovir Hydrochloride  Audio icon

Other Names: Valtrex, valacyclovir HCl
Drug Class: Opportunistic Infections and Coinfections
Chemical Image:
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valacyclovir hydrochloride
valacyclovir hydrochloride
Molecular Weight: 360.8

What is valacyclovir hydrochloride?


Valacyclovir hydrochloride is an antiviral prescription medicine approved by the U.S. Food and Drug Administration (FDA) for the following treatment and prevention uses for certain types of herpes simplex virus (HSV):

  • To treat initial or recurrent episodes of genital herpes in healthy adults.
  • To prevent genital herpes outbreaks in adults infected with HIV.
  • To reduce the risk of transmitting genital herpes to other people.
  • To treat cold sores (also known as herpes labialis or orolabial herpes) in adults and children.

Valacyclovir hydrochloride is also approved for the following treatment uses for varicella zoster virus (VZV) infections:

  • To treat shingles (also known as herpes zoster) in adults.
  • To treat chicken pox (also known as primary varicella infection) in children.

HSV and VZV infections are opportunistic infections. An opportunistic infection is an infection that occurs more frequently or is more severe in people with weakened immune systems—such as those infected with HIV—than in people with healthy immune systems.

Valacyclovir hydrochloride can also be used “off-label” to prevent and treat other opportunistic infections of HIV infection. “Off-label” use refers to use of an FDA-approved medicine in a manner different from that described on the medicine label. Good medical practice and the best interests of a patient sometimes require that a medicine be used “off-label.”


What HIV-related opportunistic infections is valacyclovir hydrochloride used for?


The Guidelines for the Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents, prepared by the Centers for Disease Control and Prevention (CDC), the National Institutes of Health (NIH), and the HIV Medicine Association of the Infectious Diseases Society of America (IDSA-HIVMA), includes recommendations on the HIV-related uses of valacyclovir hydrochloride to:

  • Prevent:
    • Orolabial lesions (cold sores) and genital lesions caused by HSV infection from recurring (called secondary prophylaxis or maintenance therapy). (The orolabial lesion use is an “off-label” use.)
    • VZV infections, including shingles and chicken pox, from occurring in certain people who come in contact with someone who has active shingles or chicken pox. (This is called post-exposure prophylaxis and is an “off-label” use.)
  • Treat:
    • HSV infections, including orolabial lesions (cold sores) and genital lesions.
    • VZV infections, including shingles and chicken pox. 


What should I tell my health care provider before taking valacyclovir hydrochloride?


Before taking valacyclovir hydrochloride, tell your health care provider:

  • If you are allergic to valacyclovir hydrochloride or any other medicines.
  • About any medical conditions you have or have had, for example, diabetes or liver problems.
  • About anything that could affect your ability to take medicines, such as difficulty swallowing or remembering to take pills.
  • If you are pregnant or plan to become pregnant. Valacyclovir hydrochloride should be used during pregnancy only if the potential benefit justifies the potential risk to the unborn baby.
  • If you are breastfeeding or plan to breastfeed. Do not breastfeed if you are infected with HIV.
  • About other prescription and nonprescription medicines, vitamins, nutritional supplements, and herbal products you are taking or plan to take. Ask your health care provider if there are interactions between valacyclovir hydrochloride and the other medicines you take.

Ask your health care provider about possible side effects from valacyclovir hydrochloride. Your health care provider will tell you what to do if you have side effects.


How should I take valacyclovir hydrochloride?


Take valacyclovir hydrochloride according to your health care provider’s instructions. Your health care provider will tell you how much valacyclovir hydrochloride to take and when to take it. Before you start valacyclovir hydrochloride and each time you get a refill, read any printed information that comes with your medicine.


How should valacyclovir hydrochloride be stored?


  • Store valacyclovir hydrochloride caplets at room temperature, 59°F to 77°F (15°C to 25°C).
  • Store valacyclovir hydrochloride suspension between 36°F to 46°F (2°C to 8°C) in a refrigerator. Discard after 28 days.
  • Keep valacyclovir hydrochloride in a tightly closed container.
  • Safely throw away valacyclovir hydrochloride that is no longer needed or expired (out of date).
  • Keep valacyclovir hydrochloride and all medicines out of reach of children.


Where can I find more information about valacyclovir hydrochloride?


More information about valacyclovir hydrochloride is available:


The above Patient Version drug summary is based on the following FDA label(s): Caplet.


Last Reviewed: May 7, 2013

Last Updated: May 7, 2013