Valacyclovir

This information from Lexicomp® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.

Brand Names: US

Valtrex

Brand Names: Canada

AG-Valacyclovir; APO-Valacyclovir; Auro-Valacyclovir; BIO-Valacyclovir [DSC]; DOM-Valacyclovir [DSC]; JAMP Valacyclovir; JAMP-Valacyclovir; Mar-Valacyclovir [DSC]; MYLAN-Valacyclovir; PMS-Valacyclovir; Priva-Valacyclovir [DSC]; PRO-Valacyclovir; RIVA-Valacyclovir; SANDOZ Valacyclovir; TEVA-Valacyclovir; Valtrex

What is this drug used for?

  • It is used to treat shingles, cold sores, or certain other herpes infections.
  • It is used to treat chickenpox.
  • It may be given to you for other reasons. Talk with the doctor.

What do I need to tell my doctor BEFORE I take this drug?

  • If you are allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.

This drug may interact with other drugs or health problems.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Do not take this drug for longer than you were told by your doctor.
  • If you are taking this drug for cold sores, it will not cure cold sores. Talk with your doctor.
  • This drug is not a cure for herpes infections. Talk with the doctor.
  • If you have genital herpes, this drug will not stop it from spreading. Do not have any kind of sex when you have sores or other signs of genital herpes. Genital herpes can also be spread if you do not have any signs. Do not have any kind of sex without using a latex or polyurethane condom. Talk with your doctor.
  • If you are 65 or older, use this drug with care. You could have more side effects.
  • Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
  • Feeling confused.
  • Change in the way you act.
  • Mood changes.
  • Hallucinations (seeing or hearing things that are not there).
  • Trouble speaking.
  • Shakiness, trouble moving around, or stiffness.
  • Seizures.
  • Very bad and sometimes deadly blood problems like thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) have happened with this drug in some people. Call your doctor right away if you feel very tired or weak or have any bruising or bleeding; dark urine or yellow skin or eyes; pale skin; change in the amount of urine passed; change in eyesight; change in strength on 1 side is greater than the other, trouble speaking or thinking, or change in balance; or fever.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Headache.
  • Upset stomach or throwing up.
  • Stomach pain.
  • Diarrhea.
  • Feeling tired or weak.
  • Period (menstrual) pain.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to your national health agency.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • Take with or without food.
  • Drink lots of noncaffeine liquids unless told to drink less liquid by your doctor.
  • If you are taking this drug to treat cold sores, chickenpox, shingles, or genital herpes, start this drug as soon as you can after your signs start. This drug may not help if you start taking it too late.
  • If you are on dialysis and are taking this drug on the day you get dialysis, take it after your dialysis. If you have questions, talk with your doctor.
  • Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
  • A liquid (suspension) can be made if you cannot swallow pills. Talk with your doctor or pharmacist.

Liquid (suspension):

  • If a liquid (suspension) is made, shake well before use.
  • Measure liquid doses carefully. Use the measuring device that comes with this drug. If there is none, ask the pharmacist for a device to measure this drug.

What do I do if I miss a dose?

  • Take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.

How do I store and/or throw out this drug?

Tablets:

  • Store at room temperature in a dry place. Do not store in a bathroom.

Liquid (suspension):

  • If a liquid (suspension) is made from the tablets, store in a refrigerator. Do not freeze. Throw away any part not used after 28 days.

All products:

  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This generalized information is a limited summary of diagnosis, treatment, and/or medication information. It is not meant to be comprehensive and should be used as a tool to help the user understand and/or assess potential diagnostic and treatment options. It does NOT include all information about conditions, treatments, medications, side effects, or risks that may apply to a specific patient. It is not intended to be medical advice or a substitute for the medical advice, diagnosis, or treatment of a health care provider based on the health care provider’s examination and assessment of a patient’s specific and unique circumstances. Patients must speak with a health care provider for complete information about their health, medical questions, and treatment options, including any risks or benefits regarding use of medications. This information does not endorse any treatments or medications as safe, effective, or approved for treating a specific patient. UpToDate, Inc. and its affiliates disclaim any warranty or liability relating to this information or the use thereof. The use of this information is governed by the Terms of Use, available at https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.

Last Reviewed Date

2022-12-26

Copyright

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Last Updated

Monday, December 12, 2022