Valacyclovir
Generic Valtrex
Valacyclovir (val ay SYE kloe veer) is a generic medication prescribed for infections caused by the herpes virus. These include cold sores, genital herpes, chickenpox, and shingles. Valacyclovir belongs to a group of drugs called antivirals.
Valacyclovir (val ay SYE kloe veer) is a generic medication prescribed for infections caused by the herpes virus. These include cold sores, genital herpes, chickenpox, and shingles. Valacyclovir belongs to a group of drugs called antivirals.
- Generic
- • Tablet
- • 500mg
- • 30 Tablets
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Introduction
Written by Helen Marshall, BPharm, MRPharmS
Medically reviewed by Amber Watson, PharmD
Updated on 6/30/23
This article describes valacyclovir’s uses, side effects, and more. You’ll also find some coupon options to help save on the cost of valacyclovir.
Side effects of valacyclovir
Valacyclovir may cause mild or serious side effects. More common mild side effects of valacyclovir and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.
To learn more about valacyclovir’s side effects, see this article or ask your doctor or pharmacist. You can also refer to the prescribing information for valacyclovir listed in the “Article resources” section.
Mild side effects
More common mild side effects reported with valacyclovir are listed below.
This article doesn’t include all possible mild side effects of the drug. To learn more about valacyclovir’s side effects, refer to the prescribing information for valacyclovir listed in the “Article resources” section.
With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.
Valacyclovir oral tablet’s mild side effects include:
- headache
- nausea
- abdominal pain
- mild allergic reaction*
* For details about this side effect, see the “Interactions and warnings for valacyclovir” section.
Serious side effects
Serious side effects of valacyclovir are listed below.
This article doesn’t include all possible serious side effects of the drug. To learn more about valacyclovir’s side effects, refer to the prescribing information for valacyclovir listed in the “Article resources” section.
With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.
In general, valacyclovir’s serious side effects include:
- brain and nervous system problems, such as hallucinations (seeing or hearing something that’s not really there), confusion, or seizures
- acute (sudden) kidney failure
- depression
- low levels of platelets and white blood cells
- increased liver enzymes, which could be a sign of liver problems
- severe allergic reaction*
* For details about this side effect, see the “Interactions and warnings for valacyclovir” section.
Uses of valacyclovir
The Food and Drug Administration (FDA) approves prescription drugs such as valacyclovir for certain conditions. Approved uses for valacyclovir are described below.
Use for cold sores
Doctors may prescribe valacyclovir oral tablet for treating cold sores. It’s used for this purpose in adults and children ages 12 years and older. It’s usually prescribed as a short-term treatment.
Cold sores are caused by infection with the herpes simplex virus. Even with treatment, this virus can stay in your body and cause recurrent outbreaks of cold sores.
With cold sores, fluid-filled blisters develop on or near your lips or on other parts of your face. The blisters burst and form painful, oozing sores before they scab over and heal. About 24 hours before the blister develops, you’ll typically have tingling, burning, or itching on your lips or face.
Valacyclovir should be taken as soon as possible when you notice symptoms of a cold sore developing. The medication stops the virus from multiplying, which can help the cold sore clear up faster. It’s not known whether taking valacyclovir after the cold sore has appeared will make it clear up any faster.
Doctors may not prescribe valacyclovir oral tablet in certain situations, such as for people with a weak immune system.
Use for shingles
Doctors may prescribe valacyclovir oral tablet for treating shingles. It’s used for this purpose in adults. It’s usually prescribed as a short-term treatment.
Shingles is caused by infection with the herpes zoster virus, which is the same virus that causes chickenpox. This virus can stay inactive in your nerves for many years after you recover from chickenpox. If it becomes active again, this causes shingles.
With shingles, you develop a painful, burning rash with blisters that ooze, usually on one side of your body, neck, or face. A few days before the rash develops, you may notice tingling, burning, itching, or numbness in your skin.
Valacyclovir is most effective when started as soon as possible after symptoms start and within 48 hours of the rash developing. The medication stops the virus from multiplying, which can help shingles get better faster. It’s not known if valacyclovir is effective when started more than 72 hours after the rash develops.
Doctors may not prescribe valacyclovir oral tablet in certain situations, such as for widespread shingles infections or for people with a weak immune system.
Use for chickenpox
Doctors may prescribe valacyclovir oral tablet for treating chickenpox. It’s used for this purpose in children ages 2–17 years. It’s usually prescribed as a short-term treatment.
Chickenpox is caused by infection with the herpes zoster virus. With chickenpox, you have an itchy rash with blisters that break open and ooze before they scab over and heal.
Valacyclovir should be started within 24 hours of the rash developing. It stops the virus from multiplying, which can help chickenpox get better faster. It’s not known if valacyclovir is effective when started more than 24 hours after the rash develops.
Doctors may not prescribe valacyclovir oral tablet in certain situations, such as for children with a weak immune system.
Use for genital herpes
Doctors may prescribe valacyclovir oral tablet for treating and helping prevent genital herpes. It’s used for this purpose in adults. It may be prescribed as a long-term or short-term treatment.
Genital herpes is a sexually transmitted infection (STI) caused by the herpes simplex virus. Even with treatment, this virus can stay in your body and cause further outbreaks of genital herpes.
With genital herpes, you develop blisters on your genitals or around your anus or buttocks. The blisters burst and form painful, oozing sores before they scab over and heal. You may have tingling, burning, or itching before the blisters develop.
Valacyclovir stops the herpes virus from multiplying. It can be taken to treat an episode of genital herpes and help it clear up faster. With a first episode, treatment should be started within 72 hours of your symptoms starting. With future outbreaks, treatment should be started within 24 hours of your symptoms starting.
Doctors may also prescribe valacyclovir as a long-term treatment to help prevent outbreaks of genital herpes. And they may prescribe it to lower the risk of transmitting genital herpes during sexual activity. You’ll still need to use barrier methods, such as condoms, during sex and avoid having sex during an outbreak. (During an outbreak, genital herpes can transmit even while taking valacyclovir and using barrier methods.)
Doctors may not prescribe valacyclovir oral tablet in certain situations, such as for people with a weak immune system. However, they may prescribe it to help prevent outbreaks of genital herpes in people with HIV.
Common questions about valacyclovir
Below you’ll find answers to some commonly asked questions about valacyclovir.
How does valacyclovir compare with acyclovir?
Acyclovir (Zovirax) is an antiviral medication prescribed for the same uses as valacyclovir. These drugs are similar. In fact, valacyclovir is converted into acyclovir in your body.
Valacyclovir and acyclovir are similarly effective. But they’re given in different doses and come in different forms. Depending on the infection, valacyclovir may be taken less often than acyclovir. Valacyclovir only comes as an oral tablet. Acyclovir comes as an oral tablet, capsule, and suspension, as well as a topical cream and ointment. Acyclovir also comes as a liquid solution that’s given as an intravenous (IV) infusion (an injection into your vein given over time).
To find out more about how these drugs compare, talk with your doctor. They can recommend the treatment that’s best for you.
Is valacyclovir an antibiotic?
No, valacyclovir is not an antibiotic. Instead, it’s an antiviral medication.
Antibiotics treat infections caused by bacteria. Antivirals treat infections caused by viruses. Valacyclovir treats infections caused by herpes viruses.
To learn more about the types of herpes virus infections that valacyclovir can treat, see the “Uses of valacyclovir” section.
What brand names are available for valacyclovir?
Valacyclovir is available as the brand-name drug Valtrex. If you’re interested in taking the brand-name version of valacyclovir, talk with your doctor.
A generic medication is an identical copy of the active drug in a brand-name medication. (An active drug is an ingredient that makes a medication work.) Generics usually cost less than brand-name drugs. And they’re thought to be as safe and effective as the brand-name versions.
Can valacyclovir cause long-term side effects?
Yes, in some cases valacyclovir may cause long-term side effects. These can last for a while after you’ve stopped taking the drug. They may also happen if you take the drug for a long time, for example to help prevent outbreaks of genital herpes.
Examples of long-term side effects include:
- liver or kidney problems, such as hepatitis (inflammation in the liver) and acute (sudden) kidney failure
- depression
Talk with your doctor to learn more about these side effects and how to best manage them. Ask your doctor for more information about how long these side effects of valacyclovir may last.
Is there a chance of spreading herpes while taking valacyclovir?
Yes, there’s a chance herpes virus can transmit to another person while taking valacyclovir. The herpes virus is highly capable of being transmitted. The virus can pass to another person even while you’re taking medication to treat the infection. The risk of transmitting the herpes virus is highest when there are oozing sores or blisters. This risk gets lower as the sores scab over and heal.
If you take valacyclovir to treat a herpes infection, the medication helps relieve your symptoms faster. So it can reduce the length of time the virus can affect others.
If you take valacyclovir to lower the risk of transmitting genital herpes, it’s still possible to pass on the infection. You should continue to use barrier methods, such as condoms, to avoid transmitting the virus through sexual activity.
How does valacyclovir work? And how long does it take to start working?
Valacyclovir works by stopping herpes viruses from multiplying and reducing their ability to transmit. This helps your immune system (your body’s defense system) to clear the infection faster. However, there will still be some virus left in your body. There’s no medication that completely cures herpes infections.
Valacyclovir starts working as soon as you start taking it. But it may take a few days to get relief from your symptoms .
If you’d like to know more about this, talk with your doctor or pharmacist.
Interactions and warnings for valacyclovir
Below, you’ll find information about valacyclovir’s possible interactions and warnings.
Interactions of valacyclovir
Valacyclovir isn’t known to interact with any medications or supplements. (Interactions can affect how a drug works.) But this doesn’t mean drug interactions with valacyclovir won’t happen or be reported sometime. For instance, medications created at a later time could interact with valacyclovir.
Because of this, you should ask your doctor and pharmacist about possible interactions with valacyclovir. They can check for any interactions that may affect you, such as those with:
- vaccines
- foods or alcohol
- other drugs
Warnings for valacyclovir
Some people should not take valacyclovir, and others should take it cautiously.
Valacyclovir could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether valacyclovir is a safe option for you.
Ask your doctor about specific warnings for valacyclovir, and be sure to tell your doctor about your:
- current health, including any allergies to medications
- past health conditions or surgeries
Allergic reaction
Valacyclovir can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.
If you’ve had an allergic reaction to valacyclovir or any of its ingredients, your doctor will likely not prescribe valacyclovir. They can tell you about medications that are safer options for you.
A mild allergic reaction may cause the following symptoms:
A severe allergic reaction may cause the following symptoms:
- swelling under your skin, usually in your hands, feet, eyelids, or lips
- swelling of your mouth, throat, or tongue, which can cause breathing problems
If you have an allergic reaction to valacyclovir, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.
Overdose of valacyclovir
You should not take more valacyclovir than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.
If you think you’ve taken too much valacyclovir, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.
Pregnancy or breastfeeding and valacyclovir
Information about valacyclovir and pregnancy and breastfeeding is described below.
Valacyclovir and pregnancy
It’s not known whether valacyclovir should be taken during pregnancy. If you have genital herpes, your doctor may recommend that you take valacyclovir or another treatment. That’s because this infection can pass to a newborn during delivery and may cause harm.
If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.
Valacyclovir and breastfeeding
It’s not known whether valacyclovir should be taken while breastfeeding. If you’re breastfeeding or planning to do so, talk with your doctor before taking this medication.
What to ask your doctor
This article describes valacyclovir’s uses and side effects, ways to save on cost, and more. Let your doctor know if you have questions about valacyclovir or would like more details about it.
Here’s a list of some possible questions you may want to ask your doctor:
- How long should I take valacyclovir?
- What alternative treatments are available?
- Are there risks of harm from not taking treatment for herpes infection?
Article resources
- Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
- Sexually transmitted infections treatment guidelines, genital herpes. (2021). https://www.cdc.gov/std/treatment-guidelines/herpes.htm
- STI Tx quick guide: Herpes — Genital (HSV)/In pregnancy. (2021). https://www.cdc.gov/stiapp/herpes-genital_pregnancy.html
- Valacyclovir tablet. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/4bd97421-1e0a-40a6-a66b-f5f14e827eb3/spl-doc
Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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