Valtrex (Valacyclovir) Drug Information

  • Why is this medication prescribed?

    Valtrex (valacyclovir) is used to treat herpes zoster (shingles) and genital herpes. It does not cure herpes infections but decreases pain and itching, helps sores to heal, and prevents new ones from forming.

    This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

  • How should this medicine be used?

    Valtrex (valacyclovir) comes as a tablet to take by mouth. It is usually taken every 8 hours (three times a day) for 7 days to treat shingles. To treat genital herpes it is usually taken twice a day for 5 days. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take Valtrex (valacyclovir) exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor. Use this medication as soon as possible after symptoms appear.

    Continue to take Valtrex (valacyclovir) even if you feel well. Do not stop taking Valtrex (valacyclovir) without talking to your doctor.

  • Other uses for this medicine

    This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

  • What special precautions should I follow?

    Before taking Valtrex (valacyclovir):

    • tell your doctor and pharmacist if you are allergic to estrogen, progestin, or any other medications.
    • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking. Be sure to mention any of the following: acetaminophen (APAP, Tylenol); antibiotics such as ampicillin (Principen), clarithromycin (Biaxin),erythromycin (E.E.S., E-Mycin, Erythrocin), isoniazid (INH, Nydrazid), metronidazole (Flagyl),minocycline (Dynacin, Minocin), rifabutin (Mycobutin), rifampin (Rifadin, Rimactane), tetracycline (Sumycin), and troleandomycin (TAO) (not available in the U.S.); anticoagulants ('blood thinners') such as warfarin (Coumadin); antifungals such as griseofulvin (Fulvicin, Grifulvin, Grisactin), fluconazole (Diflucan), itraconazole (Sporanox), and ketoconazole (Nizoral); atorvastatin (Lipitor); clofibrate (Atromid-S); cyclosporine (Neoral, Sandimmune); bosentan (Tracleer); cimetidine (Tagamet); danazol (Danocrine); delavirdine (Rescriptor); diltiazem (Cardizem, Dilacor, Tiazac); fluoxetine (Prozac, Sarafem, in Symbyax); HIV protease inhibitors such as indinavir (Crixivan) and ritonavir (Norvir); medications for seizures such as carbamazepine (Tegretol), felbamate (Felbatol), lamotrigine (Lamictal), oxcarbazepine (Trileptal), phenobarbital (Luminal, Solfoton), phenytoin (Dilantin), primidone (Mysoline), and topiramate (Topamax); modafinil (Provigil); morphine (Kadian, MS Contin, MSIR, others); nefazodone; rifampin (Rimactane, in Rifadin, in Rifater); oral steroids such as dexamethasone (Decadron, Dexone), methylprednisolone (Medrol), prednisone (Deltasone), and prednisolone (Prelone); temazepam (Restoril); theophylline (Theobid, Theo-Dur); thyroid medication such as levothyroxine (Levothroid, Levoxyl, Synthroid); verapamil (Calan, Covera, Isoptin, Verelan); vitamin C; and zafirlukast (Accolate). Your doctor may need to change the doses of your medications or monitor you carefully for side effects.
    • if you are taking Beyaz, Safyral, Yasmin or Yaz tell your doctor and pharmacist if you are taking any of the medications listed above or any of the following: angiotensin-converting enzyme (ACE) inhibitors such as benazepril (Lotensin), enalapril (Vasotec), and lisinopril (Prinivil, Zestril); angiotensin II antagonists such as irbesartan (Avapro), losartan (Cozaar), and valsartan (Diovan); aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) and naproxen (Aleve, Naprosyn); diuretics ('water pills') such as amiloride (Midamor), spironolactone (Aldactone), and triamterene (Dyrenium); eplerenone (Inspra); heparin; or potassium supplements. Before taking Beyaz or Safyral, also tell your doctor or pharmacist if you are taking cholestyramine (Locholest, Prevalite, Questran),a folate supplement, methotrexate (Trexall), pyrimethamine (Daraprim), sulfasalazine (Azulfidine), or valproic acid (Depakene, Stavzor).
    • tell your doctor what herbal products you are taking, especially St. John's wort.
    • tell your doctor if you have or have ever had blood clots in your legs, lungs, or eyes; thrombophilia (condition in which the blood clots easily); coronary artery disease (clogged blood vessels leading to the heart); cerebrovascular disease (clogging or weakening of the blood vessels within the brain or leading to the brain); stroke or mini-stroke; an irregular heartbeat; heart disease; a heart attack; chest pain; diabetes that has affected your circulation; headaches that come along with other symptoms such as vision changes, weakness, and dizziness; high blood pressure; breast cancer; cancer of the lining of the uterus, cervix, or vagina; liver cancer, liver tumors, or other types of liver disease; yellowing of the skin or eyes during pregnancy or while you were using hormonal contraceptives (birth control pills, patches, rings, implants, or injections); unexplained abnormal vaginal bleeding; adrenal insufficiency (condition in which the body does not produce enough of certain natural substances needed for important functions such as blood pressure); or kidney disease. Also tell your doctor if you have recently had surgery or have been unable to move around for any reason. Your doctor may tell you that you should not take certain types of oral contraceptives or that you should not take any type of oral contraceptive if you have or have had any of these conditions.
    • Also tell your doctor if anyone in your family has had breast cancer, if you are overweight, and if you have or have ever had problems with your breasts such as lumps, an abnormal mammogram (breast x-ray), or fibrocystic breast disease (swollen, tender breasts and/or breast lumps that are not cancer); high blood cholesterol or fats; diabetes; asthma; toxemia (high blood pressure during pregnancy); heart attack; chest pain; seizures; migraine headaches; depression; gallbladder disease; jaundice (yellowing of the skin or eyes); and excessive weight gain and fluid retention (bloating) during the menstrual cycle.
    • do not take oral contraceptives if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking oral contraceptives, call your doctor immediately.
    • if you miss periods while you are taking oral contraceptives, you may be pregnant. If you are using a 91-tablet packet and you miss one period, call your doctor. If you are using another type of packet according to the directions and you miss one period, you may continue to take your tablets. However, if you have not taken your tablets as directed and you miss one period or if you have taken your tablets as directed and you miss two periods, call your doctor and use another method of birth control until you have a pregnancy test. If you are using a 28-tablet packet that contains only active tablets, you will not expect to have periods on a regular basis, so it may be hard to tell if you are pregnant. If you are using this type of oral contraceptive, call your doctor and have a pregnancy test if you experience symptoms of pregnancy such as nausea, vomiting, and breast tenderness, or if you suspect you may be pregnant.
    • if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking oral contraceptives.
    • you should know that oral contraceptives may cause a spotty darkening of the skin, especially on the face. If you have experienced changes in your skin color during pregnancy or while you were taking oral contraceptives in the past, you should avoid exposure to real or artificial sunlight while you are taking oral contraceptives. Wear protective clothing, sunglasses, and sunscreen.
    • tell your doctor and pharmacist if you wear contact lenses. If you notice changes in vision or ability to wear your lenses while taking oral contraceptives, see an eye doctor.
  • What special dietary instructions should I follow?

    Before taking Valtrex (valacyclovir):

    • tell your doctor and pharmacist if you are allergic to acyclovir (Zovirax), Valtrex (valacyclovir), or any other drugs.
    • tell your doctor and pharmacist what prescription and nonprescription medications you are taking, especially cimetidine (Tagamet), probenecid (Benemid), and vitamins.
    • tell your doctor if you have or have ever had kidney or liver disease, problems with your immune system, human immunodeficiency virus infection (HIV), or acquired immunodeficiency syndrome (AIDS).
    • tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking Valtrex (valacyclovir), call your doctor.
  • What should I do if I forget a dose?

    Take the missed dose as soon as you remember it, and take any remaining doses for that day at evenly spaced intervals. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

  • What side effects can this medication cause?

    Valtrex (valacyclovir) may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

    • headache
    • upset stomach
    • vomiting
    • diarrhea or loose stools
    • constipation

    If you experience any of the following side effects, call your doctor immediately:

    • rash
    • itching
    • confusion
    • yellowness of the skin or eyes
    • fever
    • blood in the urine

    If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online [at] or by phone [1-800-332-1088].

  • What storage conditions are needed for this medicine?

    Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom). Throw away any medication that is outdated or no longer needed. Talk to your pharmacist about the proper disposal of your medication.

  • In case of emergency/overdose

    In case of overdose, call your local poison control center at 1-800-222-1222. If the victim has collapsed or is not breathing, call local emergency services at 911.

  • What other information should I know?

    Keep all appointments with your doctor and the laboratory. Your doctor will order certain lab tests to check your response to Valtrex (valacyclovir).

    Do not have sexual intercourse when you can see the genital herpes lesions. However, genital herpes can be spread even when there are no symptoms.

    Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription. If you still have symptoms of infection after you finish the Valtrex (valacyclovir), call your doctor.

    It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

  • Brand Names

    • Valtrex® Caplets