Health Library Antiviral Medicines for ChickenpoxFrom Healthwise

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.

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

Antiviral medicines may be prescribed to people who have been in contact with someone who has chickenpox. Antiviral medicines are generally given to people who are more likely to become seriously ill or develop complications from chickenpox. These medicines need to be started within 24 hours of the first signs of chickenpox rash.

Oral antivirals may safely be given to people who:

• Have long-term illnesses, such as skin or lung diseases.
• Are receiving short-term corticosteroid medicine, such as people being treated for asthma.
• Are receiving long-term treatment with certain medicines containing salicylates, such as people with arthritis.

Intravenous antivirals are usually recommended for:

• 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.

Antiviral eye ointment is recommended for people who have chickenpox blisters in their eyes.

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.
• Pregnant women unless they have complications of chickenpox.

Antiviral medicines can shorten the time a person is ill or reduce the severity of symptoms. But they aren't used regularly if a person's symptoms are not severe or the illness is not causing problems for the family.

Antiviral medicines may work best to protect family members of a person with chickenpox from getting chickenpox.

• Often the first person in a family to get chickenpox is not able to get an antiviral medicine soon enough (within 24 hours of the first sign of rash).
• Other family members have time to look for the first signs of chickenpox and watch for the chickenpox rash. At the first sign of rash, they may be able to take an antiviral medicine. Other family members are also more likely to have severe symptoms because they have been in close contact with someone who has chickenpox and have been exposed to higher concentrations of the virus.

Antiviral medicines may shorten the length of illness from chickenpox, cause fewer blisters to form, and help blisters heal faster.

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

Antiviral medicines have few side effects. They include:

• Headache or feelings of general illness (malaise).
• Nausea and vomiting.
• Diarrhea or constipation. This is rare.
• Kidney problems in people who receive large doses of acyclovir by rapid injection into a vein. This is rare.

The effect of antiviral medicines on pregnant women and their fetuses is not known.

The effect of antiviral medicines on immunity to chickenpox is not known.

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

Consider the following when deciding whether to treat a family member with antiviral medicines:

• Antiviral medicines are expensive. The cost of treatment includes both the medicine and visits to a health professional's office.
• Treatment with antiviral medicines may reduce the length of time you can pass the chickenpox virus to other people.
• It is not clear whether antiviral medicines reduce lost time from work, school, or day care.

Acyclovir (Zovirax) is the most prescribed antiviral medicine. It has fewer side effects than the other antiviral medicines. But it does not reduce itching, nor does it stop the spread of the chickenpox virus from one person to another.

People who take acyclovir need to drink extra liquids to prevent kidney problems. People who have kidney problems need to take a lower dose of acyclovir.

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Author:	Debby Golonka, MPH	Last Updated: May 21, 2008
Medical Review:	Michael J. Sexton, MD - Pediatrics Thomas Emmett Francoeur, MDCM, CSPQ, FRCPC - Pediatrics
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