Antiviral Medicines for Chickenpox

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Antiviral Medicines for Chickenpox


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Antiviral medicines can be taken by mouth (orally), given by injection into a vein (intravenous, or IV), or applied on the skin (topically). Acyclovir is the antiviral medicine used most often to treat chickenpox (varicella). But other antivirals may be used.

Antiviral eye ointments are also available. They can be used on your eyes to treat chickenpox blisters.

How It Works

Antiviral medicines stop the growth of the chickenpox (varicella-zoster) virus.

Why It Is Used

Antiviral medicines may be prescribed if a person has been exposed to chickenpox and can't get the chickenpox vaccine or antibodies to help prevent chickenpox.

These medicines may also be used to help treat chickenpox.

Antiviral medicines are typically given to people who are more likely to become seriously ill or to have complications from chickenpox, such as:

  • People who have a long-term illness, such as skin or lung disease.
  • People with impaired immune systems.
  • Pregnant women with serious complications of chickenpox.
  • Babies born early or babies who have a low birth weight and whose mother had chickenpox.

These medicines are usually NOT recommended for:

  • Healthy children or adults as a way to prevent them from having chickenpox if they have been exposed to the illness.
  • Healthy children as a way to treat chickenpox.

Antiviral medicines can help protect family members of a person with chickenpox from getting chickenpox. But they aren't used regularly if a person's symptoms are not severe or the illness is not causing problems for the family.

How Well It Works

Antiviral medicines may shorten the length of illness from chickenpox, cause fewer blisters to form, and help blisters heal faster. They work best if taken right after the first signs of chickenpox rash appear.

It is not known whether antiviral medicines reduce the chance of complications of chickenpox. Antiviral medicines may reduce the complications of chickenpox, such as varicella pneumonia, in people who have impaired immune systems.

Side Effects

All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.

Here are some important things to think about:

  • Usually the benefits of the medicine are more important than any minor side effects.
  • Side effects may go away after you take the medicine for a while.
  • If side effects still bother you and you wonder if you should keep taking the medicine, call your doctor. He or she may be able to lower your dose or change your medicine. Do not suddenly quit taking your medicine unless your doctor tells you to.

Call 911 or other emergency services right away if you have:

  • Trouble breathing.
  • Swelling of your face, lips, tongue, or throat.
  • Seizures.

Call your doctor right away if you have:

  • Hives.
  • Dizziness, or if you are feeling faint.
  • A fast heartbeat.
  • Confusion.
  • A change in vision.

Common side effects of this medicine include:

  • Feelings of general illness (malaise).
  • Headache.
  • Nausea and vomiting.
  • Diarrhea.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Taking medicine

Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.

There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.

Advice for women

If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.


Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.

Complete the new medication information form (PDF)(What is a PDF document?) to help you understand this medication.


ByHealthwise Staff
Primary Medical ReviewerJohn Pope, MD - Pediatrics
Specialist Medical ReviewerThomas Emmett Francoeur, MD, MDCM, CSPQ, FRCPC - Pediatrics
Last RevisedMay 14, 2012

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