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Antiviral Drugs for Seasonal Flu
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Antiviral Drugs General Information
What are flu antiviral drugs?
Flu antiviral drugs are prescription drugs (pills, liquid, or an inhaled powder) that decrease the ability of flu viruses to reproduce. While CDC recommends a yearly seasonal flu vaccine as the first and most important step in protecting against seasonal flu, antiviral drugs are a second line of defense against the flu. Antiviral drugs are not sold over-the-counter and are different from antibiotics. You can only get them if you have a prescription from your doctor or health care provider.
What are the treatment benefits of flu antiviral drugs?
When used for treatment, antiviral drugs can reduce the severity of flu symptoms and shorten the time you are sick by 1 or 2 days. Also, among hospitalized patients treatment with antiviral drugs can reduce the time spent in the hospital, ICU admissions, the development of pneumonia and death. For treatment, influenza antiviral drugs work best when started within two days after becoming sick. However, hospitalized patients may benefit from treatment even if started more than 48 hours after symptoms begin.
How effective are antiviral drugs at preventing the flu?
When used to prevent the flu, antiviral drugs are about 70% to 90% effective against susceptible viruses (i.e., viruses that are not resistant to the antiviral medication). It’s important to remember that flu antiviral drugs are not a substitute for getting a flu vaccine.
Antiviral Drugs for the 2010-2011 Season
What flu antiviral drugs does CDC recommend for use in the United States for the 2010-2011 season?
CDC has issued interim guidance on which antiviral drugs to use during the 2010-2011 flu season. Antiviral medications currently recommended for the 2010-2011 flu season include oseltamivir (Tamiflu®
and zanamivir (Relenza®. Tamiflu® is available as a pill or liquid and Relenza® is a powder that is inhaled. This recommendation is based upon recent viral surveillance and antiviral resistance data. These data indicate that more than 99% of currently circulating influenza virus strains are sensitive to these medications.
Antiviral drugs differ in terms of who can take them, how they are given, and their dose (which can vary depending on a person's age or medical conditions). Your doctor will help decide whether you should take an antiviral drug and, if so, which one you should use.
Use of Antiviral Drugs
Who should take antiviral drugs for flu?
CDC has provided guidelines on the use of antiviral drugs (see Interim Guidance on the Use of Influenza Antiviral Agents During the 2010-2011 Influenza Season). It’s very important that antiviral drugs be used early to treat flu in people who are very sick with flu (for example, people who are in the hospital) and people who are sick with flu and have a high risk condition or in an age group that increases their chance of getting serious flu complications (see box). Other people may also be treated with antiviral drugs by their doctor this season. Most healthy people with flu, however, do not need to be treated with antiviral drugs.
Can people who are not in a high-risk group receive antiviral drugs?
Yes, they can if prescribed by a healthcare professional. Consult with your doctor if you are ill or have been exposed to someone with influenza to determine if you should take antiviral drugs.
How can I get an antiviral drug for flu?
Antiviral drugs must be prescribed by a healthcare professional and are not available over-the-counter. Studies have shown that flu antiviral drugs work best for treatment if they are started within 2 days of getting sick. Therefore, especially if you are in a high risk group or have a severe illness that might be the flu, contact your doctor early.
How long should antiviral drugs be taken?
The length of time antiviral drugs should be taken depends on how they are being used. To prevent flu, antiviral drugs should be taken once a day for as long as flu viruses are circulating in a given setting or for 10 days if given after a specific exposure to a person with flu. To treat flu, antiviral drugs are taken twice a day for 5 days. Longer treatment regimens may be prescribed for hospitalized patients or persons with compromised immune systems.
What side effects can occur with flu antiviral drugs?
Side effects differ for each antiviral drug.
Tamiflu® has been in use since 1999. The most common side effects are nausea or vomiting which usually happen in the first 2 days of treatment. Taking Tamiflu® with food can reduce the chance of getting these side effects.
Relenza® has been in use since 1999. The most common side effects are dizziness, sinusitis, runny or stuffy nose, cough, diarrhea, nausea, or headache. Relenza® may also cause wheezing and trouble breathing, especially in people with lung disease.
Confusion and abnormal behavior leading to injury has been observed rarely in people with the flu, mostly children in Japan, who were treated with Tamiflu® or Relenza®. Flu can also cause these behaviors. But persons taking these drugs should be closely monitored for signs of unusual behavior or problems thinking clearly. This behavior should be immediately reported to a health care provider.
If an antiviral drug has been prescribed for you, ask your doctor to explain how to use the drug and any possible side effects.
Can flu antiviral drugs help with other illnesses such as the common cold?
No. Flu antiviral drugs only work against flu viruses. They will not help reduce symptoms from the common cold or any other flu-like illnesses caused by viruses other than flu viruses. Many other viruses cause respiratory illnesses and flu-like symptoms besides influenza.
Can antiviral drugs be helpful for people unable to take the flu vaccine?
Yes. CDC and ACIP recommend the use of antiviral drugs for people who cannot get the flu vaccine. For example, people that have a severe allergy to eggs and, thus, cannot get the flu vaccine which is grown in eggs, or people who previously have had Guillain-Barré syndrome (GBS) associated with getting a flu vaccination. In addition, taking antiviral drugs may be recommended among persons that may not have a good immune response to the flu vaccine.
Should people use antiviral drugs before or after receiving the live attenuated influenza vaccine (LAIV) called FluMist®?
Antiviral medications should not be taken from 48 hours through 2 weeks after getting LAIV. LAIV is one of two types of flu vaccine. It is given as a nasal spray and contains weakened, live virus. Flu antiviral drugs taken from 48 hours before through 2 weeks after getting LAIV can lower or prevent the vaccinated person from responding to the vaccine and the person may not get immune protection from the vaccine.
However, antiviral drugs can be taken with the inactivated (i.e., killed) flu vaccine, also known as the "flu shot."
Can antiviral drugs be given even if a person is not tested for flu or if a flu test does not indicate that they have influenza?
Yes. Influenza testing is not required for antiviral drugs to be prescribed. Testing can be done if recommended by your health care provider.
Tests are available that can test for flu viruses in as little as 30 minutes or less. However, results from these rapid tests are not accurate; a rapid test could be negative even though the person really does have the flu. So other information in addition to influenza test results, if conducted, need to be factored into decisions about using antiviral drugs. One consideration will be information about whether influenza is circulating in the community.
Can influenza antiviral drugs be used in pregnant women?
Yes. Pregnant women and women within the first 2 weeks after delivery are at increased risk of severe illness from flu. Both the CDC and the American College of Obstetrics and Gynecology recommend that pregnant women with suspected or lab test-proven flu get antiviral treatment with oseltamivir for flu. Antiviral drugs are "Pregnancy Category C" medications, indicating that no studies have been conducted to assess the safety of these drugs for pregnant women for medication licensure. However, no safety problems have been identified for use of these medications for pregnant women or in their unborn children during extensive use of antivirals during the 2009-10 pandemic.
Oseltamivir (Tamiflu® & Zanamivir (Relenza®
What are oseltamivir (Tamiflu® and zanamivir (Relenza®?
Tamiflu® and Relenza® are antiviral drugs known as neuraminidase inhibitors that fight against both influenza A and B viruses.
Oseltamivir
(brand name Tamiflu® is approved to both treat and prevent flu in people one year of age and older.
Zanamivir (brand name Relenza® is approved to treat flu in people 7 years and older and to prevent flu in people 5 years and older.
What are the possible side effects of oseltamivir (Tamiflu®?
Tamiflu® has been in use since 1999. The most common side effects are nausea and vomiting which usually happen in the first 2 days of treatment. Taking Tamiflu® with food can reduce the chance of getting these side effects. The Food and Drug Administration (FDA) now requires that neuraminidase inhibitors have information in the package labeling that warns that people with the flu, especially children, may be at an increased risk of self-injury and confusion shortly after taking and should be closely monitored for signs of unusual behavior. This precaution was added after the FDA received post marketing reports (mostly from Japan) about persons (primarily among children and adolescents) who had purposefully injured themselves or been delirious while using neuraminidase inhibitors to treat influenza. Most reports were among persons using Tamiflu. The reports appear to be uncommon. For more information, visit the Food & Drug Administration's MedWatch page.
What should be done if complications occur while taking oseltamivir (Tamiflu®?
Contact a healthcare professional immediately if someone taking Tamiflu® shows any signs of unusual behavior.
What are the possible side effects of zanamivir (Relenza®?
Relenza® has been in use since 1999. The most common side effects are diarrhea, nausea, sinusitis, runny or stuffy nose, bronchitis, cough, headache, dizziness, and ear, nose and throat infections. Some persons, mostly those who already had a chronic lung disease such as asthma, have reported serious breathing problems such as wheezing or shortness of breath after taking Relenza®. In rare cases, people have had an allergic reaction to the drug, including rashes and edema (a build-up of fluid in body-tissue) of the face and throat.
The FDA now requires that neuraminidase inhibitors have information in the package labeling that warns that people with the flu, especially children, may be at an increased risk of self-injury and confusion shortly after taking and should be closely monitored for signs of unusual behavior. This precaution was added after the FDA received post marketing reports (mostly from Japan) about persons (primarily children and adolescents) who had purposefully injured themselves or been delirious while using neuraminidase inhibitors to treat influenza. For more information, visit the Food & Drug Administration's MedWatch page.
Who is at risk for complications from zanamivir (Relenza®?
Persons with chronic lung diseases such as asthma or chronic obstructive pulmonary disease are not recommended to use Relenza® (zanamivir), as some patients have reported difficulty breathing after inhaling the drug.
What should be done if complications while taking zanamivir (Relenza® occur?
If you side effects while taking Relenza® talk to your healthcare provider immediately.
Amantadine (Symmetrel® & Rimantadine (Flumadine®
What are amantadine (Symmetrel® and rimantadine (Flumadine®?
Amantadine (Symmetrel® and rimantadine (Flumadine® are antiviral drugs known as adamantanes that have been used in the past to fight against influenza A viruses, but not influenza B viruses.
However, these medications are not now recommended by CDC for influenza treatment or prevention due to high levels of resistance among circulating influenza A viruses.
On this page…
- Antiviral Drugs General Information
- Antiviral Drugs for the 2010-2011 Season
- Use of Antiviral Drugs
- Oseltamivir (Tamiflu® & Zanamivir (Relenza®
- Amantadine (Symmetrel® & Rimantadine (Flumadine®
Antiviral Drugs General Information
What are flu antiviral drugs?
Flu antiviral drugs are prescription drugs (pills, liquid, or an inhaled powder) that decrease the ability of flu viruses to reproduce. While CDC recommends a yearly seasonal flu vaccine as the first and most important step in protecting against seasonal flu, antiviral drugs are a second line of defense against the flu. Antiviral drugs are not sold over-the-counter and are different from antibiotics. You can only get them if you have a prescription from your doctor or health care provider.
What are the treatment benefits of flu antiviral drugs?
When used for treatment, antiviral drugs can reduce the severity of flu symptoms and shorten the time you are sick by 1 or 2 days. Also, among hospitalized patients treatment with antiviral drugs can reduce the time spent in the hospital, ICU admissions, the development of pneumonia and death. For treatment, influenza antiviral drugs work best when started within two days after becoming sick. However, hospitalized patients may benefit from treatment even if started more than 48 hours after symptoms begin.
How effective are antiviral drugs at preventing the flu?
When used to prevent the flu, antiviral drugs are about 70% to 90% effective against susceptible viruses (i.e., viruses that are not resistant to the antiviral medication). It’s important to remember that flu antiviral drugs are not a substitute for getting a flu vaccine.
Antiviral Drugs for the 2010-2011 Season
What flu antiviral drugs does CDC recommend for use in the United States for the 2010-2011 season?
CDC has issued interim guidance on which antiviral drugs to use during the 2010-2011 flu season. Antiviral medications currently recommended for the 2010-2011 flu season include oseltamivir (Tamiflu®
and zanamivir (Relenza®. Tamiflu® is available as a pill or liquid and Relenza® is a powder that is inhaled. This recommendation is based upon recent viral surveillance and antiviral resistance data. These data indicate that more than 99% of currently circulating influenza virus strains are sensitive to these medications. Antiviral drugs differ in terms of who can take them, how they are given, and their dose (which can vary depending on a person's age or medical conditions). Your doctor will help decide whether you should take an antiviral drug and, if so, which one you should use.
Use of Antiviral Drugs
Who should take antiviral drugs for flu?
CDC has provided guidelines on the use of antiviral drugs (see Interim Guidance on the Use of Influenza Antiviral Agents During the 2010-2011 Influenza Season). It’s very important that antiviral drugs be used early to treat flu in people who are very sick with flu (for example, people who are in the hospital) and people who are sick with flu and have a high risk condition or in an age group that increases their chance of getting serious flu complications (see box). Other people may also be treated with antiviral drugs by their doctor this season. Most healthy people with flu, however, do not need to be treated with antiviral drugs.
Can people who are not in a high-risk group receive antiviral drugs?
Yes, they can if prescribed by a healthcare professional. Consult with your doctor if you are ill or have been exposed to someone with influenza to determine if you should take antiviral drugs.
How can I get an antiviral drug for flu?
Antiviral drugs must be prescribed by a healthcare professional and are not available over-the-counter. Studies have shown that flu antiviral drugs work best for treatment if they are started within 2 days of getting sick. Therefore, especially if you are in a high risk group or have a severe illness that might be the flu, contact your doctor early.
How long should antiviral drugs be taken?
The length of time antiviral drugs should be taken depends on how they are being used. To prevent flu, antiviral drugs should be taken once a day for as long as flu viruses are circulating in a given setting or for 10 days if given after a specific exposure to a person with flu. To treat flu, antiviral drugs are taken twice a day for 5 days. Longer treatment regimens may be prescribed for hospitalized patients or persons with compromised immune systems.
What side effects can occur with flu antiviral drugs?
Side effects differ for each antiviral drug.
Tamiflu® has been in use since 1999. The most common side effects are nausea or vomiting which usually happen in the first 2 days of treatment. Taking Tamiflu® with food can reduce the chance of getting these side effects.
Relenza® has been in use since 1999. The most common side effects are dizziness, sinusitis, runny or stuffy nose, cough, diarrhea, nausea, or headache. Relenza® may also cause wheezing and trouble breathing, especially in people with lung disease.
Confusion and abnormal behavior leading to injury has been observed rarely in people with the flu, mostly children in Japan, who were treated with Tamiflu® or Relenza®. Flu can also cause these behaviors. But persons taking these drugs should be closely monitored for signs of unusual behavior or problems thinking clearly. This behavior should be immediately reported to a health care provider.
If an antiviral drug has been prescribed for you, ask your doctor to explain how to use the drug and any possible side effects.
Can flu antiviral drugs help with other illnesses such as the common cold?
No. Flu antiviral drugs only work against flu viruses. They will not help reduce symptoms from the common cold or any other flu-like illnesses caused by viruses other than flu viruses. Many other viruses cause respiratory illnesses and flu-like symptoms besides influenza.
Can antiviral drugs be helpful for people unable to take the flu vaccine?
Yes. CDC and ACIP recommend the use of antiviral drugs for people who cannot get the flu vaccine. For example, people that have a severe allergy to eggs and, thus, cannot get the flu vaccine which is grown in eggs, or people who previously have had Guillain-Barré syndrome (GBS) associated with getting a flu vaccination. In addition, taking antiviral drugs may be recommended among persons that may not have a good immune response to the flu vaccine.
Should people use antiviral drugs before or after receiving the live attenuated influenza vaccine (LAIV) called FluMist®?
Antiviral medications should not be taken from 48 hours through 2 weeks after getting LAIV. LAIV is one of two types of flu vaccine. It is given as a nasal spray and contains weakened, live virus. Flu antiviral drugs taken from 48 hours before through 2 weeks after getting LAIV can lower or prevent the vaccinated person from responding to the vaccine and the person may not get immune protection from the vaccine.
However, antiviral drugs can be taken with the inactivated (i.e., killed) flu vaccine, also known as the "flu shot."
Can antiviral drugs be given even if a person is not tested for flu or if a flu test does not indicate that they have influenza?
Yes. Influenza testing is not required for antiviral drugs to be prescribed. Testing can be done if recommended by your health care provider.
Tests are available that can test for flu viruses in as little as 30 minutes or less. However, results from these rapid tests are not accurate; a rapid test could be negative even though the person really does have the flu. So other information in addition to influenza test results, if conducted, need to be factored into decisions about using antiviral drugs. One consideration will be information about whether influenza is circulating in the community.
Can influenza antiviral drugs be used in pregnant women?
Yes. Pregnant women and women within the first 2 weeks after delivery are at increased risk of severe illness from flu. Both the CDC and the American College of Obstetrics and Gynecology recommend that pregnant women with suspected or lab test-proven flu get antiviral treatment with oseltamivir for flu. Antiviral drugs are "Pregnancy Category C" medications, indicating that no studies have been conducted to assess the safety of these drugs for pregnant women for medication licensure. However, no safety problems have been identified for use of these medications for pregnant women or in their unborn children during extensive use of antivirals during the 2009-10 pandemic.
Oseltamivir (Tamiflu®
& Zanamivir (Relenza®What are oseltamivir (Tamiflu®
and zanamivir (Relenza®?Tamiflu® and Relenza® are antiviral drugs known as neuraminidase inhibitors that fight against both influenza A and B viruses.
Oseltamivir
(brand name Tamiflu® is approved to both treat and prevent flu in people one year of age and older.Zanamivir
(brand name Relenza® is approved to treat flu in people 7 years and older and to prevent flu in people 5 years and older.What are the possible side effects of oseltamivir (Tamiflu®
?Tamiflu® has been in use since 1999. The most common side effects are nausea and vomiting which usually happen in the first 2 days of treatment. Taking Tamiflu® with food can reduce the chance of getting these side effects. The Food and Drug Administration (FDA) now requires that neuraminidase inhibitors have information in the package labeling that warns that people with the flu, especially children, may be at an increased risk of self-injury and confusion shortly after taking and should be closely monitored for signs of unusual behavior. This precaution was added after the FDA received post marketing reports (mostly from Japan) about persons (primarily among children and adolescents) who had purposefully injured themselves or been delirious while using neuraminidase inhibitors to treat influenza. Most reports were among persons using Tamiflu. The reports appear to be uncommon. For more information, visit the Food & Drug Administration's MedWatch
page.What should be done if complications occur while taking oseltamivir (Tamiflu®
?Contact a healthcare professional immediately if someone taking Tamiflu® shows any signs of unusual behavior.
What are the possible side effects of zanamivir (Relenza®
?Relenza® has been in use since 1999. The most common side effects are diarrhea, nausea, sinusitis, runny or stuffy nose, bronchitis, cough, headache, dizziness, and ear, nose and throat infections. Some persons, mostly those who already had a chronic lung disease such as asthma, have reported serious breathing problems such as wheezing or shortness of breath after taking Relenza®. In rare cases, people have had an allergic reaction to the drug, including rashes and edema (a build-up of fluid in body-tissue) of the face and throat.
The FDA now requires that neuraminidase inhibitors have information in the package labeling that warns that people with the flu, especially children, may be at an increased risk of self-injury and confusion shortly after taking and should be closely monitored for signs of unusual behavior. This precaution was added after the FDA received post marketing reports (mostly from Japan) about persons (primarily children and adolescents) who had purposefully injured themselves or been delirious while using neuraminidase inhibitors to treat influenza. For more information, visit the Food & Drug Administration's MedWatch
page.Who is at risk for complications from zanamivir (Relenza®
?Persons with chronic lung diseases such as asthma or chronic obstructive pulmonary disease are not recommended to use Relenza® (zanamivir), as some patients have reported difficulty breathing after inhaling the drug.
What should be done if complications while taking zanamivir (Relenza®
occur?If you side effects while taking Relenza® talk to your healthcare provider immediately.
Amantadine (Symmetrel®
& Rimantadine (Flumadine®What are amantadine (Symmetrel®
and rimantadine (Flumadine®?Amantadine (Symmetrel®
and rimantadine (Flumadine® are antiviral drugs known as adamantanes that have been used in the past to fight against influenza A viruses, but not influenza B viruses.However, these medications are not now recommended by CDC for influenza treatment or prevention due to high levels of resistance among circulating influenza A viruses.
