Valacyclovir

Generic name: valacyclovir
Brand name: Valtrex
Drug class: Purine nucleosides

Medically reviewed by  A Ras MD.

What is valacyclovir used for?

Valacyclovir is a prescription medicine that is used to treat herpes infections. It is used to treat shingles. Valacyclovir is also used to treat cold sores. It is used to treat chickenpox.

Valacyclovir may be given to you for other reasons. Talk to your doctor.

Description

Valacyclovir hydrochloride USP is the hydrochloride salt of the L-valyl ester of the antiviral drug acyclovir.

Valacyclovir tablets, USP are for oral administration. Each tablet contains valacyclovir hydrochloride USP equivalent to 500 mg or 1 gram valacyclovir and the inactive ingredients croscarmellose sodium, FD&C Blue #2, hydrogenated castor oil, hypromellose, polyethylene glycol, polysorbate 80, starch (corn), and titanium dioxide.

The chemical name of valacyclovir hydrochloride is L-valine, 2-[(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)methoxy]ethyl ester, monohydrochloride. It has the following structural formula:

Before taking valacyclovir, tell your doctor:

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

This medicine 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 valacyclovir 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 valacyclovir?

• Tell all of your health care providers that you take valacyclovir. This includes your doctors, nurses, pharmacists, and dentists.
• Do not take valacyclovir for longer than you were told by your doctor.
• If you are taking valacyclovir for cold sores, it will not cure cold sores. Talk with your doctor.
• This medicine is not a cure for herpes infections. Talk with the doctor.
• If you have genital herpes, valacyclovir 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 valacyclovir 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.

How is valacyclovir best taken?

Use valacyclovir 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 valacyclovir to treat cold sores, chickenpox, shingles, or genital herpes, start valacyclovir as soon as you can after your signs start. This medicine may not help if you start taking it too late.
• Keep taking valacyclovir 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 valacyclovir. If there is none, ask the pharmacist for a device to measure valacyclovir.

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.

What are the side effects of valacyclovir that I need to call my doctor about immediately?

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 valacyclovir 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 valacyclovir?

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

If overdose is suspected:

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.

How do I store and/or throw out valacyclovir?

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.