Active Ingredient

Valacyclovir

Valacyclovir is an antiviral medication used to treat infections caused by certain types of viruses. It helps manage conditions like herpes simplex and herpes zoster.

This medication is often prescribed to reduce the severity and duration of outbreaks.

Written By Douglas C. Goldberg, MD

Reviewed By Philip Schein, MD

Last Updated 28 Nov 2025

Available Valacyclovir Brands

Valtrex

Strengths 500mg, 1000mg

Valacyclovir Uses

Valacyclovir is commonly used to treat viral infections and manage symptoms associated with them.

Treatment of cold sores (herpes labialis)
Management of genital herpes outbreaks
Reduction of shingles (herpes zoster) symptoms
Prevention of recurrent herpes simplex infections
Reduction of transmission of genital herpes

How Valacyclovir Works

Valacyclovir works by slowing the growth and spread of the herpes virus in the body. It does not cure the infections but helps reduce the symptoms and speed up healing.

As an antiviral agent, it interferes with the viral replication process, making it harder for the virus to multiply.

This helps the immune system control the infection more effectively.

Common side effects of Valacyclovir

Not everyone experiences side effects from Valacyclovir, and many are mild and temporary.

Headache
Nausea
Dizziness
Stomach pain
Fatigue
Diarrhea
Vomiting

If you experience serious or persistent symptoms, contact your doctor.

Take Valacyclovir as directed by your healthcare provider.
Avoid close contact with others when symptoms are present to prevent spreading the virus.
Stay hydrated, especially if you experience any stomach upset.
Avoid alcohol as it may increase the risk of side effects.
Inform your doctor of any other medications you are taking to avoid interactions.

Always consult your doctor if you have any concerns or questions about taking this medication.

Frequently Asked Questions

How quickly does Valacyclovir start working?

Valacyclovir starts to work soon after you take it, but it may take a few days to notice an improvement in symptoms.

Can Valacyclovir prevent herpes transmission?

Valacyclovir can help reduce the risk of transmitting herpes to others, but it is not a substitute for safe practices.

Is Valacyclovir safe for long-term use?

Your doctor can advise on the safety of long-term use based on your specific health needs and condition.

Can I take Valacyclovir with other medications?

It’s important to inform your doctor of all medications you are taking to avoid potential interactions.

What should I do if I miss a dose of Valacyclovir?

If you miss a dose, take it as soon as you remember, unless it’s nearly time for your next dose. Do not double up doses.