Medications and Drugs

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Brand Names: Valtrex

Generic Name: valacyclovir (Pronunciation: val a SYE kloe veer)

• What is valacyclovir (Valtrex)?
• What are the possible side effects of valacyclovir (Valtrex)?
• What is the most important information I should know about valacyclovir (Valtrex)?
• What should I discuss with my healthcare provider before taking valacyclovir (Valtrex)?
• How should I take valacyclovir (Valtrex)?
• What happens if I miss a dose (Valtrex)?
• What happens if I overdose (Valtrex)?
• What should I avoid while taking valacyclovir (Valtrex)?
• What other drugs will affect valacyclovir (Valtrex)?
• Where can I get more information?

What is valacyclovir (Valtrex)?

Valacyclovir is an antiviral drug. It slows the growth and spread of the herpes virus so that the body can fight off the infection. Valacyclovir will not cure herpes, but it can lessen the symptoms of the infection.

Valacyclovir is used to treat infections caused by herpes viruses in adults and children. Illnesses caused by herpes viruses include genital herpes, cold sores, shingles, and chickenpox.

Valacyclovir is used to treat cold sores in children who are at least 12 years old, and to treat chickenpox in children who are at least 2 years old.

Valacyclovir may also be used for other purposes not listed in this medication guide.

Valtrex 1 gram

oblong, blue, imprinted with VALTREX 1 gram

Valtrex 500 mg

oblong, blue, imprinted with VALTREX 500 mg

What are the possible side effects of valacyclovir (Valtrex)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop taking valacyclovir and call your doctor right away if you have any of the following signs of a serious side effect that can harm red blood cells:

• fever, easy bruising or bleeding;
• red spots on the skin (not related to herpes or chickenpox);
• bloody diarrhea, vomiting;
• pale or yellowed skin;
• weakness or fainting; or
• urinating less than usual or not at all.

Call your doctor at once if you have any of these other serious side effects:

• pain in your lower back;
• drowsiness, mood changes, increased thirst, loss of appetite, nausea and vomiting;
• swelling, weight gain, feeling short of breath;
• confusion, agitation, aggression, hallucinations, trouble concentrating;
• feeling shaky or unsteady;
• problems with speech or vision; or
• seizure (convulsions).

Less serious side effects may include:

• nausea, stomach pain;
• headache, dizziness, tired feeling, depression;
• joint pain;
• menstrual pain;
• mild skin rash; or
• stuffy nose, sore throat.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about valacyclovir (Valtrex)?

Before taking valacyclovir, tell your doctor if you have HIV/AIDS, a weak immune system, kidney disease (or if you are on dialysis), or if you have had a kidney or bone marrow transplant.

Valacyclovir can be harmful to the kidneys, and these effects are increased when it is used together with other medicines that can harm the kidneys. Tell your doctor about all other medications you are using. You may need dose adjustments or special tests when taking certain medications together with valacyclovir.

Treatment with valacyclovir should be started as soon as possible after the first appearance of symptoms (such as tingling, burning, blisters).

Herpes virus can be passed from an infected mother to her baby during childbirth. If you have genital herpes, it is very important to prevent herpes lesions during your pregnancy so that you do not have a genital lesion when your baby is born.

Valacyclovir will not prevent the spread of genital herpes. Herpes infections are contagious and you can infect other people even while you are taking with valacyclovir.

Stop taking valacyclovir and call your doctor right away if you have any signs of a serious side effect that can harm red blood cells, such as: fever, easy bruising or bleeding, red spots on the skin (not related to herpes or chickenpox), bloody diarrhea, vomiting, pale or yellowed skin, weakness, fainting, or urinating less than usual or not at all.

Do not give valacyclovir to a child unless it has been prescribed by a doctor.