Valacyclovir: Uses & Side Effects

Valacyclovir is an antiviral drug. It slows
the growth and spread of the herpes virus to help the body fight the infection.
Valacyclovir is used to treat infections caused by herpes viruses, including
genital herpes, cold sores, and shingles (herpes zoster) in adults. Valacyclovir
is used to treat cold sores in children who are at least 12 years old, or
chickenpox in children who are at least 2 years old.

How should I take valacyclovir?

Take valacyclovir exactly as it was
prescribed for you. Follow all directions on your prescription label. Do not
take this medicine in larger or smaller amounts or for longer than recommended.

Start taking valacyclovir as soon as possible
after the first appearance of symptoms (such as tingling, burning, blisters).
This medicine might not be as effective if you first start taking it 1 or 2
days after the start of your symptoms.

Some herpes infections need to be
treated for longer than others.
Use this medicine
for the full prescribed length of time. Your symptoms may improve before the
infection is completely cleared. Skipping doses may increase the risk of your
virus becoming resistant to antiviral medicine.

You may take valacyclovir with or without

Drink plenty of water while you are taking
valacyclovir to keep your kidneys working properly.

Lesions caused by herpes viruses should be
kept as clean and dry as possible. Wearing loose clothing may help to prevent
irritation of the lesions.

Store valacyclovir tablets at room
temperature away from moisture and heat.


You should not use this medicine if you are
allergic to valacyclovir or acyclovir (Zovirax).

To make sure valacyclovir is safe for you,
tell your doctor if you have:

  • kidney disease (or if you are on dialysis).
  • HIV/AIDS, or other conditions that can weaken the immune system.
  • a history of kidney transplant or bone marrow transplant.

It is not known whether this medicine will
harm an unborn baby. However, 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 can pass into breast milk and
may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

Do not give valacyclovir to a child without
medical advice.


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

Call your doctor at once if you have:

  • confusion, aggression, or you feel shaky or unsteady.
  • hallucinations (seeing or hearing things that are not real).
  • problems with speech.
  • a seizure (convulsions).
  • kidney problems–little or no urination, painful or difficult
    urination, swelling in your feet or ankles, feeling tired or short of breath.

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, pale skin.
  • unusual bleeding (nosebleeds, bleeding gums).
  • red or pink urine, little or no urination.
  • red spots on the skin (not related to herpes or chickenpox).
  • feeling weak or tired.
  • stomach pain, bloody diarrhea, vomiting.
  • swelling in your face, hands, or feet.

Side effects may be more likely in adults
who are 65 or older.

Common valacyclovir side effects may

  • nausea, stomach pain.
  • headache.
  • rash.
  • tired feeling.


Valacyclovir can harm your kidneys. This
effect is increased when you also use certain other medicines, including
antivirals, chemotherapy, injected antibiotics, medicine for bowel disorders,
medicine to prevent organ transplant rejection, injectable osteoporosis
medication, and some pain or arthritis medicines (including aspirin, Tylenol,
Advil, and Aleve).

Remember, keep this and all other medicines
out of the reach of children, never share your medicines with others, and use
valacyclovir only for the indication prescribed.

Always consult your healthcare provider to
ensure the information displayed on this page applies to your personal

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