Antiviral Drugs and Influenza

by CDC

(Page 2 of 2)

Four antiviral medications (amantadine, rimantadine, zanamavir and oseltamivir) have been approved by the U.S. Food and Drug Administration (FDA) for treatment of influenza. However, you will need to begin taking the medication within 2 days after becoming sick. When used in this manner, these medications can reduce influenza symptoms and may shorten the time you are sick by 1 or 2 days. They also may make you less contagious. All of these medications must be prescribed by a doctor and taken for 3-5 consecutive days (5 days for oseltamivir and zanamivir). The 4 antiviral medications are effective only against influenza viruses. They will not help symptoms associated with the common cold or many other influenza-like illnesses caused by viruses that circulate in the winter.

All four antiviral medications (amantadine, rimantadine, and oseltamivir) also are approved by the FDA and are commercially available for use in the United States to prevent influenza. All of these medications are prescription drugs, and a doctor should be consulted before the drugs are used. When used for prevention, they are about 70% to 90% effective in preventing illness in healthy adults.

All of the antiviral medications may be effective for influenza A viruses. However, only oseltamivir and zanamivir are effective for influenza B viruses. Also, recent evidence indicates that a high proportion of currently circulating influenza A viruses in the United States have developed resistance to amantadine and rimantadine.

All of the antiviral medications are different in terms of who can take them, how they are given, any dosing changes based on age or medical conditions, and side effects. Your doctor can help decide whether you should take an antiviral drug and which one you should use.

Use of Antiviral Medications

Antiviral medications are most often used to help control influenza outbreaks in institutions, for example in nursing homes or in hospital wards, where people at high risk for complications from influenza are in close contact with each other. Antiviral medications also have been used on cruise ships or similar settings to help control influenza outbreaks.

In the event of an outbreak, public health practice is to combine the use of influenza vaccine and antiviral medications. For example, nursing home residents and staff are given vaccine during an outbreak and also are given antiviral medications to prevent influenza until the vaccine takes effect (about 2 weeks). This practice continues as long as influenza is occurring in that setting.

Doctors also can prescribe influenza antiviral medications to people not living in institutional settings, but treatment must begin within 2 days of the onset of symptoms for the drugs to be effective. Although all antiviral medications lessen symptoms and shorten the duration of illness, only one (oseltamivir) has been shown in a study to reduce lower respiratory tract complications requiring antibiotics. They do not cure influenza outright.

When considering the use of antiviral medications it is important to remember that most healthy people recover from influenza without complications.

Who Should Get Antiviral Medications

People who are at high risk of serious complications from influenza may benefit most from antiviral medications. This includes: people 65 years of age and older, children 12-23 months of age, people with chronic medical conditions (for example, heart or lung disease, diabetes), and pregnant women. (Note that none of the antiviral medications is approved for use in children less than 1 year of age.) Although CDC has provided guidelines for health-care professionals on the use of antiviral drugs, your doctor will decide whether you should receive antiviral medications this season. The guidelines for use of influenza antiviral medications are not intended as recommendations for use of these medications in other situations, such as outbreaks of new strains of avian influenza.

For Treatment: If you become sick with influenza-like symptoms this season, your doctor first may give you a test to find out whether you have influenza. (Symptoms include fever (usually high), headache, tiredness, a sore throat and dry cough, nasal congestion, and body aches.) Your doctor also will consider a number of factors before making a treatment decision, such as your risk for complications from influenza.

For Prevention: In the event of an influenza outbreak in a home, institution, or community, your doctor may choose to prescribe antiviral medications to you as a preventive measure, especially if you are at high risk for complications from influenza. Also, if you are in close contact with someone who is considered at high risk for complications, you may be given antiviral medications to reduce the chances of passing influenza to the high-risk person.

What to Do If You Get Sick

Influenza (commonly called the "flu") is a contagious respiratory illness caused by influenza viruses. The information below describes common flu symptoms, how to protect yourself and those close to you from getting the flu, and what to do if you get sick with flu-like symptoms.

People May Have Different Reactions to the Flu

The flu can cause mild to severe illness and at times can lead to death. Although most healthy people recover from the flu without complications, some people, such as older people, young children, and people with certain health conditions, are at high risk for serious complications from the flu.

Know the Risks from the Flu

In some people, the flu can cause serious complications, including bacterial pneumonia, dehydration, and worsening of chronic medical conditions, such as congestive heart failure, asthma, or diabetes. Children and adults may develop sinus problems and ear infections.

Know How the Flu Spreads

The flu usually spreads from person to person in respiratory droplets when people who are infected cough or sneeze. People occasionally may become infected by touching something with influenza virus on it and then touching their mouth, nose, or eyes.

Healthy adults may be able to infect others 1 day before getting symptoms and up to 5 days after getting sick. Therefore, it is possible to give someone the flu before you know you are sick as well as while you are sick.

About the Author

www.cdc.gov
The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.