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Influenza (Flu) Antiviral Drugs and Related Information


The term "influenza" refers to illness caused by influenza virus. This is commonly also called "flu", but many different illnesses cause "flu-like" systemic and respiratory symptoms such as fever, chills, aches and pains, cough, and sore throat. In addition, influenza itself can cause many different illness patterns, ranging from mild common cold symptoms to typical "flu" to life-threatening pneumonia and other complications, including secondary bacterial infections.

This web site contains links to several sources of general information about influenza. Because vaccination is the primary means of preventing and controlling influenza, links related to influenza vaccine are listed first, followed by links related to antiviral drugs that have been approved in the United States for influenza. After the vaccine and antiviral drug links, there is a list of web sites that provide additional influenza information from United States government agencies and the World Health Organization, and a list of contacts for further inquiries.

Information provided on this web site may change frequently, and should not be used as a substitute for individual evaluation by a health care provider, or as the primary means of diagnosing influenza or determining treatment.

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Influenza Vaccine Information

Influenza vaccine is the principal method of preventing and controlling influenza. The following links provide information on general uses of vaccines and on current supply issues.

Drug Information

Uncomplicated influenza gets better with or without treatment, but may cause substantial discomfort and limitation of activity before getting better. Complications of influenza can include bacterial infections, viral pneumonia, and cardiac and other organ system abnormalities. People with chronic medical conditions may have increased risk of complications when they get influenza. Many other diseases, including serious infections such as rapidly progressive bloodstream infections, may start with symptoms that resemble influenza and may need to be considered in treatment decisions. Rapid laboratory tests can help in detecting influenza but do not exclude the possibility of other illnesses or take the place of clinical evaluation.

Many people with uncomplicated influenza use over-the-counter medicines to help lessen their symptoms. Antiviral drugs available by prescription can also help to reduce the time it takes for symptoms to improve in uncomplicated illness caused by influenza virus. Recent increases in the number and promotion of antiviral drugs for influenza have increased interest in the role of specific antiviral drugs for this condition. Other products are sometimes promoted for prevention or treatment of influenza, but may not have been tested for their actual effects against influenza.

Complications of influenza, and other illnesses that resemble influenza, may require different treatment and may need urgent medical attention. Use of antiviral drugs does not eliminate the risk of complications, and some complications (as well as other medical conditions that could be confused with influenza) can be life-threatening. In addition, influenza viruses can become resistant to specific anti-influenza antiviral drugs, and all of the drugs have side effects. Therefore, if you have new symptoms during treatment, or your symptoms persist or get worse during treatment, you should see your health care provider.

There has been a lot of recent concern about "bird flu" which can refer to a number of influenza viruses that occur in birds and could become causes of human disease in some situations. Some of the current influenza antiviral drugs are able to inhibit many of the "bird flu" viruses in the laboratory although it is not known exactly how much effect they might have against these infections in people.

Outbreaks of influenza occur every year and typically reach epidemic levels during some part of the season.  If a new variety of influenza starts to be transmitted rapidly between people, it can cause extremely widespread illness known as a pandemic.  Depending on the strain of influenza causing a future pandemic, antiviral drugs may have varying levels of usefulness.  The government is stockpiling antiviral drugs, and developing recommendations about their use, as part of pandemic preparedness efforts (see additional information at links below).

The following links lead to information such as trade names, package inserts, and other material related to the four antiviral drugs currently approved by FDA to treat acute, uncomplicated influenza.  Two related drugs, amantadine (approved 1966; Trade Name Symmetrel, also available as generic Amantadine Hydrochloride) and rimantadine (approved 1993; Trade Name Flumadine, also available as generic Rimantadine Hydrochloride), are approved for treatment and prevention of influenza A, but many strains of influenza have now become resistant to these drugs as noted in the 2006 CDC Health Alert Two newer drugs, zanamivir (approved 1999; Trade Name Relenza; no approved generics) and oseltamivir phosphate (approved 1999; Trade Name Tamiflu; no approved generics), are approved for treatment of acute uncomplicated illness due to influenza A and B. Both zanamivir and oseltamivir are approved for preventive use.  Approved ages, doses, and dosing instructions in children are different for each drug, so the individual package inserts should be checked for this information. The anti-influenza antiviral drugs are not a substitute for vaccine and are used only as an adjunct to vaccine in the control of influenza.

The antiviral drug information addresses side effects or adverse events that might be associated with each drug. Because some side effects can be serious and because viruses may become resistant when antiviral drugs are used indiscriminately, decisions on the use of these drugs should be based on individual evaluations of risk and benefit. FDA encourages reporting of serious adverse events (associated with these or any other drugs) to the MedWatch program to facilitate continued updating of risk/benefit information.

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Influenza Information from Other Web Sites

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Contacts for More Information

Information on availability of influenza vaccine:
Food and Drug Administration
Center for Biologics Evaluation and Research
Office of Communication, Training & Manufacturers Assistance
301-827-1800.  Fax: 301-827-3843


Information on drugs used to treat influenza:
Food and Drug Administration
Center for Drug Evaluation and Research
Drug Information Line
888-info-FDA or 301-827-4573.  Fax: 301-827-4577


Information on influenza prevention and control:
Centers for Disease Control and Prevention
Public Inquiries Office
800-311-3435 or 404-639-3311.  Fax: 770-488-4995

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Updated: January 17, 2006, updated March 19, 2008

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