Key Facts About Antiviral Drugs and Influenza (Flu)

On this page:

Background
Antiviral Drugs

Use of Antiviral Drugs for Treatment
Use of Antiviral Drugs for Prevention

Who Should Get Antiviral Drugs
Notes

Background

While getting a flu vaccine each year is the best way to protect you from the flu, there also are drugs that can fight against influenza viruses, offering a second line of defense against the flu. These are called “influenza antiviral drugs” and they must be prescribed by a health care professional. These drugs can be used to treat the flu or to prevent infection with flu viruses. Influenza antiviral drugs only work against influenza viruses -- they will not help treat or prevent symptoms caused by infection from other viruses that can cause symptoms similar to the flu. Antiviral drugs are used in different settings and circumstances to treat the flu and to prevent people from getting the flu:

Antiviral drugs are used to help control flu outbreaks in places where a lot of people at high risk of serious flu complications live in close contact with each other, like nursing homes or hospital wards, for example.
Antiviral drugs are used in the community setting to treat people with the flu to reduce severity of symptoms and reduce the number of days that people are sick.
Antiviral drugs are used to prevent the flu

for people who have been close to someone with the flu, or
for people that need protection from the flu but they either don’t get protection after vaccination, or the vaccine is unavailable or they can’t get the vaccine because of allergies, for example.

While most healthy people recover from the flu and don’t have serious complications, some people—such as older people, young children, and people with certain health conditions (such as asthma, diabetes, or heart disease)—are at higher risk for serious flu-related complications. It’s especially important that these people are protected from the flu.

Remember, a flu vaccine is the first and best defense against the flu, but antiviral drugs can be an important second line of defense to treat the flu or prevent flu infection.

Antiviral Drugs

There are four flu antiviral drugs approved for use in the United States. CDC has issued interim guidance on which antiviral drugs to use during the 2008-09 flu season: The four antiviral drugs are:

Oseltamivir (brand name Tamiflu ®) is approved to both treat and prevent influenza A and B virus infection in people one year of age and older.
Zanamivir (brand name Relenza ®) is approved to treat influenza A and B virus infection in people 7 years and older and to prevent influenza A and B virus infection in people 5 years and older.
Amantadine (Symmetrel®, generic) is approved to treat and prevent only influenza A viruses in people older than 1 year.
Rimantadine (Flumadine®, generic) is approved to prevent only influenza A virus infection among people older than 1 year. It is approved to treat only influenza A virus infections in people 13 and older.

Antiviral drugs differ in terms of who can take them, how they are given, their dose (which can vary depending on a person’s age or medical conditions), and side effects.

For more information, see “Information for Health Care Professionals: Using Antiviral Agents for Seasonal Influenza” or consult the package insert for each drug. Your doctor can help decide whether you should take an antiviral drug this flu season and which one you should use.

Use of Antiviral Drugs for Treatment

For treatment, influenza antiviral drugs should be started within 2 days after becoming sick. When used this way, these drugs can reduce flu symptoms and shorten the time you are sick by 1 or 2 days.

If you become sick with flu-like symptoms this season, your doctor will consider the likelihood of influenza being the cause of your illness, the number of days you have been sick, side effects of the medication, etc. before making a recommendation about using antiviral drugs. He or she may test you for influenza, but testing is not required in order for a health care provider to recommend influenza antiviral medications for you.

Use of Antiviral Drugs for Prevention

Influenza antiviral drugs also can be used to prevent influenza when they are given to a person who is not ill, but who has been or may be near a person with influenza. When used to prevent the flu, antiviral drugs are about 70% to 90% effective. It’s important to remember that flu antiviral drugs are not a substitute for getting a flu vaccine. When used for prevention, the number of days that they should be used will vary depending on a person’s particular situation.

In some instances, your doctor may choose to prescribe antiviral drugs to you as a preventive measure, especially if you are at high risk for serious flu complications and either did not get the flu vaccine or may still be at risk of illness even after vaccination. Also, if you are in close contact with someone who is considered at high risk for complications, you may be given antiviral drugs to reduce the chances of catching the flu and passing it on to the high-risk person.

Who Should Get Antiviral Drugs?

CDC has provided interim guidance for health care professionals on the use of antiviral drugs for the United States in 2008-09.

In general, antiviral drugs can be offered to anyone 1 year of age or older who wants to avoid and/or treat the flu. People who are at high risk of serious complications from the flu may benefit most from these drugs.

Antiviral drugs can also be used to prevent influenza among people with weak immune systems who may not be protected after getting a flu vaccine or who haven’t been vaccinated.

Remember, a flu vaccine is the first and best defense against seasonal flu, but antiviral drugs can be an important second line of defense to treat the flu or prevent flu infection.