What is Valtrex: Uses, Warnings & Interactions

Your healthcare provider will tell you how much medicine to use. Do not use more than directed.

This medicine works best when you take it at the first sign of a herpes breakout.

Valacyclovir tablets can be taken with food or on an empty stomach.

The healthcare provider can prepare a Valtrex oral suspension for patients who cannot take a pill.

To prevent kidney problems, drink plenty of fluids while taking valacyclovir.

Store the medicine in a closed container at room temperature.

The healthcare provider can prepare a Valtrex oral suspension for patients who cannot take a pill.

• Shake the oral suspension before measuring a dose.

• Use only a calibrated oral syringe to measure doses. The healthcare provider or pharmacist can provide one.

• Store the oral suspension in a refrigerator. Throw it out 28 days after it was given to you.

Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. 

Do not take extra medicine to make up for a missed dose.

This medicine is not right for everyone. 

Do not use it if you have had an allergic reaction to valacyclovir or acyclovir.

Make sure healthcare providers know that you or your child are taking Valtrex tablets. 

The healthcare provider who prescribes Valtrex may need follow-up visits to check the treatment progress, do blood tests, or monitor for side effects. Keep all appointments.

Tell your healthcare provider if you are pregnant or breastfeeding.

Make sure the healthcare provider knows if you have:

• Kidney injury or kidney failure

• Advanced HIV or AIDS

• Had a bone marrow or kidney transplant

Valtrex may cause serious problems, including: 

• Kidney dysfunction 

• Nervous system problems, including hallucinations and agitation

• A rare but very serious blood disorder called thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS)—symptoms are listed under Side Effects below

Older adult patients and those with kidney problems are more likely to experience kidney dysfunction or kidney failure when taking Valtrex.

Do not stop using this medicine suddenly, or change how you take it without talking to your healthcare provider.

Call your healthcare provider if your symptoms do not improve or if they get worse.

If you are taking Valtrex for genital herpes, do not have sex when you have genital herpes sores. Valacyclovir will not stop the spread of herpes during sex.

• Even when there are no sores, always use condoms made from latex or polyurethane when you have sexual contact.

Because of possible drug interactions, tell the healthcare provider about all the prescription drugs, over-the-counter medicines, and supplements being taken. Valtrex may injure the kidneys, and combining Valtrex with certain drugs can increase that risk.

Tell other healthcare providers about Valtrex treatment before they prescribe new medications.

Tell the healthcare provider about plans to get a chickenpox or shingles vaccine. That vaccine will have to wait until you’re finished with Valtrex.