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
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.
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.
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
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
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
to facilitate continued updating of risk/benefit information.
Symmetrel (amantadine). Approval, review, and labeling information
Flumadine (rimantadine). Approval, review, and labeling information
- Relenza (zanamivir). Approval,
review, and labeling information from Drugs@FDA, plus consumer
- Tamiflu (oseltamivir
phosphate). Approval, review, and labeling information from
Drugs@FDA, plus consumer information. (updated 11/13/2006)
CDC Recommends Against the Use of Amantadine and Rimantadine for the Treatment
or Prophylaxis of Influenza in the United States During the 2005–06 Influenza
Office of Generic Drugs -
Statement on Expedited Review of Generic Drug Products for the
Prophylaxis and Treatment of Illness Caused by Various Strains of
the Influenza Virus. (10/18/2004)
- Public Health Advisory:
Safe and Appropriate Use of Influenza Drugs. (Issued 1/12/2000). Health
professionals, especially prescribers, are reminded of important clinical decisions that
need to be made when considering use of anti-viral drugs for signs and symptoms of
- Emerging Viral Infections Information
on approaches to drug development for antiviral drugs.
- MedWatch site for Adverse
Event Reporting. Information and instructions for reporting of adverse events
associated with medical products such as prescription or nonprescription
drugs, biologics, and medical devices.
- Electronic Orange Book
This resource can be searched for holders of approved or discontinued
marketing applications, especially for drugs that may have more than one
source of generic preparations.
Information on availability of
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
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
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