Specifically, the Food and Drug Administration (FDA) has approved Valtrex to treat:
This article describes possible side effects of Valtrex. You can explore this overview article to learn more about Valtrex, including the drug’s uses, ways to save on cost, and more.
Valtrex is a brand-name medication that comes as an oral tablet. It’s available in a generic version called valacyclovir. This article describes possible side effects of Valtrex.
More common side effects of Valtrex
Valtrex may cause mild or serious side effects. Below are some of the more common side effects of this medication.
Commonly reported side effects of Valtrex include:
* To learn more about this side effect, see the “Side effects of Valtrex in detail” section below.
Mild side effects of Valtrex
Valtrex may cause certain mild side effects. Usually, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.
Mild side effects of Valtrex that occurred in studies include:
Valtrex may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.
* To learn more about this side effect, see the “Side effects of Valtrex in detail” section below.
† An allergic reaction is possible with Valtrex. But it wasn’t reported in the drug’s studies.
Serious side effects of Valtrex
Valtrex may cause certain serious side effects. If you have any serious side effects from Valtrex, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.
After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with Valtrex.
Serious side effects of Valtrex that occurred in studies include:
* To learn more about this side effect, see the “Side effects of Valtrex in detail” section below.
† An allergic reaction is possible with Valtrex. But it wasn’t reported in the drug’s studies.
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Side effects of Valtrex in children
For children, doctors prescribe Valtrex to treat the following conditions:
In studies, certain side effects were reported in children but not in adults. These include:
If you’d like to know more about side effects in children taking Valtrex, talk with your doctor or pharmacist.
Common questions about side effects of Valtrex
Here are answers to some common questions about side effects of Valtrex. If you have other questions, talk with your doctor or pharmacist.
How long do side effects of Valtrex usually last?
It varies. Most often, side effects of Valtrex are temporary and usually go away soon after you start or stop taking the drug.
But some side effects may last longer or have long-term effects. You can learn more about possible long-term side effects in the answer directly below.
If you have questions about what to expect with Valtrex treatment, talk with your doctor or pharmacist.
Does Valtrex cause long-term side effects?
Yes, in some cases Valtrex may cause long-term side effects. These can occur during treatment with the drug and may last for a long time.
Examples of long-term side effects reported with Valtrex include:
Talk with your doctor to learn more about these side effects and how to manage them. Ask your doctor for more information about how long these side effects of Valtrex may last.
* To learn more about this side effect, see the “Side effects of Valtrex in detail” section below.
Can Valtrex cause weight gain?
It’s unlikely. Weight gain wasn’t reported as a side effect in studies of Valtrex.
But weight gain may be a symptom of certain side effects of Valtrex. These include depression and acute (sudden) kidney failure.
If you notice weight gain while taking Valtrex, talk with your doctor. They can help determine the cause of your weight gain and suggest ways to manage it. Your doctor can also suggest options for maintaining a body weight that’s healthy for you.
Side effects of Valtrex in detail
Below you’ll find details on some of the side effects of Valtrex.
Abdominal pain
Abdominal pain was common in studies of people taking Valtrex. This side effect is usually mild.
With this side effect, you may experience pain, pressure, or discomfort just below your ribs.
Ways to manage
If you have concerns about abdominal pain with Valtrex, tell your doctor. They may recommend taking your Valtrex doses with food to help ease your symptoms.
Low levels of certain blood cells
In studies, low levels of platelets, white blood cells, and red blood cells were rare in people taking Valtrex. This side effect is usually mild.
Symptoms can vary depending on the blood cell affected and may include:
- bruising or bleeding more easily than usual
- body aches, fever, or chills
- pale-looking skin or gums
- fatigue (low energy)
In extreme cases, low levels of platelets or red blood cells can be a sign of more serious conditions. These include thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). TTP is a blood clotting disorder, and HUS is an immune system reaction that can lead to kidney failure.
Certain factors can increase the risk of TTP and HUS with Valtrex. These include having a weakened immune system and taking high doses of the drug.
Ways to manage
Talk with your doctor if you have concerns about low blood cell levels, TTP, or HUS. They’ll talk with you about symptoms to watch for and whether Valtrex is safe for you to take based on your health history.
Central nervous system effects
Central nervous system (CNS) effects were not reported in studies of Valtrex. Your CNS includes your spinal cord and brain. But there have been reports of CNS effects since the drug became available. This side effect may be serious.
With CNS effects, you may have changes to your behavior or thinking. Symptoms may include:
Certain factors can increase the risk of CNS effects with Valtrex. These include:
- being ages 65 years or older
- having a kidney problem, such as kidney failure
- taking high doses of the drug
Ways to manage
If you have CNS effects with Valtrex, contact your doctor right away. They’ll likely recommend stopping the drug so they can determine the cause of your symptoms.
For some people, Valtrex can cause an allergic reaction. But this side effect wasn’t reported in the drug’s studies.
Symptoms can be mild or serious and may include:
- itchiness
- skin rash
- swelling under the skin, usually affecting eyelids, lips, hands, or feet
- swelling of the mouth, tongue, or throat, which can make it hard to breathe
- flushing (temporary warmth, redness, or deepening of skin color)
Ways to manage
For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.
For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to Valtrex, your doctor may recommend taking a different medication instead.
Warnings for Valtrex
Below are some factors you may want to discuss with your doctor before taking Valtrex.
Warnings
It may not be safe for you to take Valtrex if you have specific health conditions. These are sometimes called drug-condition interactions. Other factors may also affect whether Valtrex is a safe treatment option for you.
Before taking Valtrex, tell your doctor about your health and medications you take. Things to consider include:
Valtrex and pregnancy
It’s not known whether Valtrex should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.
Valtrex and breastfeeding
It’s not known whether Valtrex should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.
Valtrex is not known to interact with alcohol.
But consuming alcohol with Valtrex could worsen some of the drug’s side effects. Examples include headache, dizziness, and nausea.
If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with Valtrex.
What to ask your doctor
This article describes common and serious side effects of Valtrex. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.
Here’s a list of questions you may want to ask your doctor:
- Does my risk of side effects depend on the Valtrex dosage I take?
- How do the side effects of Valtrex compare to those of other drugs that treat my condition?
- Does my health history raise my risk of side effects with Valtrex?
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.
