Valacyclovir

Valacyclovir is a prescription medication used to treat conditions caused by the herpes virus including cold sores, shingles, genital herpes outbreaks, and chicken pox. Valacyclovir belongs to a group of drugs called antivirals which work by preventing the virus from multiplying.

This medication comes in tablet form and is taken one to three times daily, with or without food.

Common side effects of valacyclovir include headaches, nausea, stomach pains, and dizziness.

Valacyclovir is a prescription medicine used in adults:

• to treat cold sores (also called fever blisters or herpes labialis)
• to treat shingles (also called herpes zoster)
• to treat or control genital herpes outbreaks in adults with normal immune systems
• to control genital herpes outbreaks in adults infected with the human immunodeficiency virus (HIV) with CD4+ cell count greater than 100 cells/mm3
• with safer sex practices to lower the chances of spreading genital herpes to others. Even with safer sex practices, it is still possible to spread genital herpes.

Valacyclovir is used in children:

• to treat cold sores (for children aged greater than or equal to 12 years)
• to treat chickenpox (for children aged 2 to less than 18 years).

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

Valacyclovir may be found in some form under the following brand names:

• Valtrex

Serious side effects may occur. See "Drug Precautions" section.

Common side effects of valacyclovir in adults include:

• headache
• nausea
• stomach pain
• vomiting
• dizziness

Side effects in HIV-1-infected adults include:

• headache
• tiredness
• rash

Other less common side effects in adults include:

• painful periods in women
• joint pain
• depression
• low blood cell counts
• changes in tests that measure how well the liver and kidneys work

The most common side effect seen in children aged less than 18 years was headache.

Talk to your healthcare provider if you develop any side effects that concern you.

These are not all the side effects of valacyclovir. For more information ask your healthcare provider or pharmacist.

Tell your doctor about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Valacyclovir may affect other medicines, and other medicines may affect valacyclovir. However, at this time no clinically significant drug-drug or drug-food interactions with valacyclovir are known. It is a good idea to keep a complete list of all the medicines you take. Show this list to your healthcare provider and pharmacist any time you get a new medicine.

Kidney failure and nervous system problems are not common, but can be serious in some patients taking valacyclovir. 

• Nervous system problems include aggressive behavior, unsteady movement, shaky movements, confusion, speech problems, hallucinations (seeing or hearing things that are really not there), seizures, and coma. Call your doctor right away if you get a nervous system problem while you are taking valacyclovir.
• Kidney failure and nervous system problems have happened in patients who already have kidney disease and in elderly patients whose kidneys do not work well due to age. Always tell your healthcare provider if you have kidney problems before taking valacyclovir. 

Do not take valacyclovir if you are allergic to any of its ingredients or to acyclovir.

Medicines can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods. In the case of valacyclovir there are no specific foods that you must exclude from your diet when receiving valacyclovir.

Before taking valacyclovir, tell your healthcare provider about all your medical conditions, including:

• if you have had a bone marrow transplant or kidney transplant, or if you have advanced HIV-1 disease or "AIDS". Patients with these conditions may have a higher chance for getting a blood disorder called thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS). TTP/HUS can result in death.
• if you have kidney problems. Patients with kidney problems may have a higher chance for getting side effects or more kidney problems with valacyclovir. Your healthcare provider may give you a lower dose of valacyclovir.
• if you are aged 65 years or older. Elderly patients have a higher chance of certain side effects. Also, elderly patients are more likely to have kidney problems. Your healthcare provider may give you a lower dose of valacyclovir.
• if you are pregnant or breastfeeding
• about all the medicines you take, including prescription and non-prescription medicines, vitamins, and herbal supplements. Valacyclovir may affect other medicines, and other medicines may affect valacyclovir. It is a good idea to keep a complete list of all the medicines you take. Show this list to your healthcare provider and pharmacist any time you get a new medicine.

Tell your doctor if you are pregnant or plan to become pregnant.

The FDA categorizes medications based on safety for use during pregnancy. Five categories - A, B, C, D, and X, are used to classify the possible risks to an unborn baby when a medication is taken during pregnancy.

This medication falls into category B. There are no well-done studies that have been done in humans with valacyclovir. In animal studies, pregnant animals were given this medication, and the babies did not show any medical issues related to this medication.

Tell your doctor if you are breastfeeding. Valacyclovir may pass into your milk and it may harm your baby. Talk with your healthcare provider about the best way to feed your baby if you are taking valacyclovir.

Take valacyclovir exactly as prescribed by your healthcare provider. Your dose of valacyclovir and length of treatment will depend on the type of herpes infection that you have and any other medical problems that you have.

• Do not stop valacyclovir or change your treatment without talking to your healthcare provider.
• Valacyclovir can be taken with or without food.
• If you are taking valacyclovir to treat cold sores, chickenpox, shingles, or genital herpes, you should start treatment as soon as possible after your symptoms start. Valacyclovir may not help you if you start treatment too late.
• If you miss a dose of valacyclovir, take it as soon as you remember and then take your next dose at its regular time. However, if it is almost time for your next dose, do not take the missed dose. Wait and take the next dose at the regular time.
• Do not take more than the prescribed number of valacyclovir tablets each day. Call your healthcare provider right away if you take too much valacyclovir.

Valacyclovir used daily with the following safer sex practices can lower the chances of passing genital herpes to your partner.

• Do not have sexual contact with your partner when you have any symptom or outbreak of genital herpes.
• Use a condom made of latex or polyurethane whenever you have sexual contact.

Valacyclovir can be compounded into a suspension if needed.

Take valacyclovir exactly as prescribed by your doctor. Follow the directions on your prescription label carefully. Your doctor will determine the best dose for you.

If you take too much valacyclovir, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

If valacyclovir is administered by a healthcare provider in a medical setting, it is unlikely that an overdose will occur. However, if overdose is suspected, seek emergency medical attention.

• Store valacyclovir tablets at room temperature, 59° to 77°F (15° to 25°C).
• If your pharmacist compounded a valacyclovir suspension for you, store your medication between 2° to 8°C (36° to 46°F) in a refrigerator. Discard after 28 days.
• Keep valacyclovir in a tightly closed container.
• Do not keep medicine that is out of date or that you no longer need.
• Keep valacyclovir and all medicines out of the reach of children.