What is Valacyclovir Used for?

Published: 2025-08-14

Updated: 2025-08-14

4 min

Valacyclovir is an antiviral prescription medication ideal for men who may have a viral infection or struggle with recurrent infections. Also known by its brand name Valtrex®, valacyclovir treats cold sores, herpes, chickenpox, and shingles in adults. Valacyclovir is available in tablet and liquid form, but only with a doctor’s prescription. 

A healthcare provider may recommend taking the medication daily for a limited amount of time, depending on your treatment needs. It’s important not to take more or less than the amount recommended by a licensed healthcare provider. In the following, learn more about the recommended uses for valacyclovir and how the medication works.

What is Valacyclovir?

Valacyclovir stops the growth of certain viral infections in the body. A healthcare provider may prescribe valacyclovir more than once to treat sudden outbreaks of herpes and other viral infections. While valacyclovir does not cure herpes or other health conditions, it can help reduce the severity of symptoms. Fortunately for kids (and adults who are not a fan of taking liquid medication), the liquid form of valacyclovir comes in a cherry flavor.

Side effects of valacyclovir

As with any medication, it’s possible to experience some side effects. You may experience the following side effects while taking valacyclovir:

• Headache

• Upset stomach

• Diarrhea

• Constipation

• Vomiting

• Rash

• Jaundice (yellowing of the eyes or skin)

Elderly adults may also experience mood swings or confusion while taking valacyclovir. If you experience severe side effects, reach out to your healthcare provider right away. They can recommend an alternate treatment that works better for you.

Key Medical Uses of Valacyclovir

When taking valacyclovir to treat infections, you can take the medication with or without food. The dosages for kids may be different from those for adults. The following outlines general dosages for treatment. The recommended dosage may vary depending on your health profile. Health experts recommend drinking plenty of water each time you take valacyclovir.

Cold sores

Children and adults can both take valacyclovir when they see a cold sore coming. While cold sores don’t always lead to symptoms, some people may experience itching, burning, or mild pain right before a cold sore pops up on their lip. Also known as fever blisters, some people are more prone to cold sores when they’re sick. If you see a cold sore, be careful not to have physical contact with others. Kissing or touching a cold sore can potentially spread it.

What is the proper dosage?

A healthcare provider may recommend around two grams of valacyclovir every 12 hours to treat cold sores.

Shingles

The varicella-zoster virus causes shingles in people who have had chickenpox before or never received the chickenpox vaccine. The most common symptom is a painful, itchy rash on one side of the body. Shingles can also reactivate the herpes virus in elderly adults. 

Over time, multiple herpes outbreaks can cause severe symptoms like changes to vision and scarring. A healthcare provider may recommend taking valacyclovir for around seven to ten days to treat shingles symptoms. Health experts discovered that those taking valacyclovir were less likely to experience long-term eye problems from shingles.

What is the proper dosage?

Generally, you take valacyclovir every eight hours for seven consecutive days to treat shingles. Health experts recommend taking the medication within 72 hours of when you first notice symptoms. The recommended dosage to treat shingles is often between one to 1000 mg (milligrams) three times daily for seven days.

Herpes

For years, there has been a misconception about HSV (herpes simplex virus). The herpes virus usually remains dormant inside nerve cells, but may be activated from skin-to-skin contact with someone who has an active infection. HSV-1 and HSV-2 are the two different types of herpes. HSV-2 is the type of herpes caused by sexual contact.

Valacyclovir may help with any pain from sores or ulcers related to genital herpes. You can use valacyclovir for one episode or recurrent flare-ups. Valacyclovir may be used along with safe sex practices to reduce the transmission of genital herpes. Health experts recommend using a barrier method like condoms or dental dams during sex in addition to receiving treatment for herpes.

What is the proper dosage?

Dosages may vary, but a healthcare provider may recommend taking valacyclovir twice daily. A healthcare provider may recommend taking valacyclovir tablets for three to five consecutive days. Dosages may vary from one gram a day to 500 mg twice daily. 

Chickenpox

Chickenpox is a contagious disease caused by the varicella-zoster virus. It can cause intense itchiness, rash, and blisters. Valacyclovir is commonly used to treat kids between the ages of two to 18 with chickenpox. A healthcare provider may recommend starting treatment within 24 hours of seeing a rash.

What is the proper dosage?

A healthcare provider may recommend taking around 20 mg three times a day for five consecutive days for children and adults with chickenpox.

What are the Risks of Taking Valacyclovir?

As with any medication, it’s possible to be allergic to valacyclovir or similar ingredients. If you feel like anything is off, don’t hesitate to let a licensed healthcare professional know as soon as possible. 

A healthcare provider may recommend a different form of treatment if you have a history of the following:

• HIV (human immunodeficiency virus infection)

• AIDS (acquired immunodeficiency syndrome)

• Liver disease

• Kidney disease

• Immunodeficiency

If you have a history of kidney complications, a healthcare provider may lower your dosage.

What Happens if I Miss a Dose?

A healthcare provider can best advise you on what to do if you miss a dose based on your treatment plan. Generally, it’s not advised to take more than the recommended dosage even if you miss one. You can take the next scheduled dosage instead of doubling your dosage. Taking more than the recommended amount may increase your risk of health complications while taking the medication.

Do Other Medications Interact with Valacyclovir?

Valacyclovir may interact with other antivirals and the following medications:

• NSAIDs

• Herbal products

• Kidney medications

• Cancer medications

Before starting valacyclovir, don’t forget to share all of the current medications and supplements you are taking with your healthcare provider. Some medications may impact the effectiveness of valacyclovir. Health experts do not advise drinking alcohol or smoking illicit substances while taking valacyclovir.

Where Can I Learn More About Valacyclovir?

A viral infection can sneak up on you in the worst of times. Itching, burning, and other symptoms can be difficult to deal with daily. Rex MD can help you get ahead of symptoms before they worsen. Rex MD offers convenient, affordable access to the FDA-approved medication valacyclovir. 

Get started today to receive treatment from the comfort of your home.