Generic Valacyclovir

Common use

Valacyclovir is an antiviral medication used to treat infections caused by herpes viruses, including genital herpes, cold sores, and shingles (herpes zoster). It is also used to manage recurrent outbreaks and reduce transmission risk to sexual partners. In patients with weakened immune systems, it helps prevent cytomegalovirus (CMV) after organ transplants. Valacyclovir works by slowing the growth and spread of the virus, though it does not cure herpes.

Dosage and direction

Valacyclovir is taken orally, typically once to three times a day depending on the type and severity of infection. It should be started at the first sign of symptoms for maximum effectiveness. The tablets can be taken with or without food and should be swallowed whole with water. Complete the full course even if symptoms improve early.

Precautions

Before using valacyclovir, inform your doctor if you have kidney disease, HIV/AIDS, or a weakened immune system. It is important to stay well hydrated during treatment to reduce the risk of kidney problems. This medicine does not prevent the spread of herpes through sexual contact, so precautions should still be taken. Elderly individuals may be more sensitive to side effects, especially related to kidney function.

Contraindications

Valacyclovir is contraindicated in patients with known hypersensitivity to valacyclovir or acyclovir. It should not be used in individuals with severely impaired renal function without dose adjustment. Caution is advised in those with conditions that affect hydration or kidney health. Always follow your healthcare provider’s instructions carefully.

Possible side effect

Common side effects include headache, nausea, stomach pain, and dizziness. Some people may experience fatigue or rash. Rare but serious side effects include hallucinations, confusion, or kidney problems, especially in older adults. If any severe or unusual symptoms occur, seek medical help promptly.

Drug interaction

Valacyclovir may interact with drugs that affect kidney function such as cyclosporine, tacrolimus, or certain NSAIDs. Concurrent use with other antivirals or chemotherapy agents may increase the risk of side effects. Always tell your doctor about all prescription and over-the-counter medicines, vitamins, or herbal supplements you are taking. Monitoring may be required when combining it with other medications.

Missed dose

If you miss a dose, take it as soon as you remember unless it is almost time for the next dose. Do not double up to make up for the missed dose. Try to take it at the same time each day to maintain even levels in your body. Skipping doses may reduce the effectiveness of the medication.

Overdose

An overdose of valacyclovir can lead to symptoms such as agitation, confusion, hallucinations, decreased urination, or seizures. In severe cases, it can cause kidney damage and requires emergency medical treatment. Overdose is more likely in patients with kidney disease. Always take the medication exactly as prescribed.

Storage

Store valacyclovir at room temperature, away from excess heat and moisture. Keep it in its original container, out of the reach of children and pets. Do not use expired medication. Ask your pharmacist about proper disposal of unused medicine.

Disclaimer

We provide only general information about medications which does not cover all directions, possible drug integrations, or precautions. Information at the site cannot be used for self-treatment and self-diagnosis. Any specific instructions for a particular patient should be agreed with your health care adviser or doctor in charge of the case. We disclaim reliability of this information and mistakes it could contain. We are not responsible for any direct, indirect, special or other indirect damage as a result of any use of the information on this site and also for consequences of self-treatment.

Clinical Verification

Last Clinically Updated: August 15, 2026

Written By

Dr. Elena Vance, PharmD

Clinical Specialist in Neuropharmacology

Fact Checked By

Marcus Thorne, MS

Biomedical Data & FDA Label Verification

Medically Reviewed By

Dr. Arthur Campbell, MD

Board-Certified Psychiatrist (ABPN)