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Fighting the Flu With Antiviral Drugs

image for meds do's and don'ts article The best way to prevent the flu is to be vaccinated every year. But what if you end up with the flu? You may need to take prescription antiviral medications if you are at high-risk for complications.

For the upcoming flu season, the Centers for Disease Control and Prevention (CDC) recommends oseltamivir, zanamivir, and peramivir for the treatment of the flu.

About Antivirals


Oseltamivir is approved for the treatment of the flu in people aged 2 weeks and older. This medication can also be taken by pregnant women.

Common side effects include nausea and vomiting. These may happen within the first 2 days of taking oseltamivir. There is also a risk, especially in children, of unusual behavior such as self-injury and confusion. It is important that people who take this medication be closely monitored.


Zanamivir, which comes in a disk inhaler, is approved for people aged 7 years and older who do not have breathing or heart problems. Common side effects include:

Like oseltamivir, zanamivir may cause unusual behavior, especially in children.


Peramivir is given through and IV and is used in adults aged 18 years and older. Common side effects include:

  • Diarrhea
  • Skin reactions
  • Confusion or delirium
  • Self-injury

Important Questions About Antivirals

Are These Medications Right for You?

Most people who get the flu do not need antivirals. Your doctor may recommend these drugs if you:

  • Have severe flu symptoms
  • Have the flu and are at high risk for serious complications

People who are at high risk include:

  • Children younger than 5 years old, but especially those younger than 2 years old
  • Adults aged 65 years and older
  • Pregnant women
  • People with chronic conditions such as asthma, heart failure, and lung disease or weakened immune systems such as patients with diabetes, and patients with HIV infection or getting chemotherapy
  • People aged 19 years and younger who are on long-term aspirin therapy

When Should You Take Them and for How Long?

Antivirals should be taken as early as possible—usually within the first 2 days of your illness. Oseltamivir and zanamivir are taken 2 times per day for 5 days. Peramivir is given as a single dose.

What Are the Benefits of Taking Antivirals Medications?

Antivirals can reduce your symptoms and shorten how long you have the flu. If you are hospitalized due to the flu, antivirals may be able to shorten your hospital stay and reduce your risk of complications. However, the benefits must be compared to the potential complications to make sure the antiviral is not doing more harm than good.

Can Antivirals Be Used to Prevent the Flu?

Antivirals can be used to prevent the flu. But the best strategy is to be vaccinated every year. The CDC recommends that everyone aged 6 months and older get the flu vaccine as soon as it becomes available.


Centers for Disease Control and Prevention

Flu—US Department of Health and Human Services


Health Canada

Public Health Agency of Canada


Influenza antiviral medications: Summary for clinicians. Centers for Disease Control and Prevention website. http://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm. Updated February 25, 2015. Accessed July 24, 2015.

Influenza antiviral treatment and prophylaxis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 7, 2015. Accessed July 25, 2015.

People at high risk of developing flu-related complications. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/flu/about/disease/high_risk.htm. Updated January 8, 2015. Accessed July 24, 2015.

Seasonal flu shot: Questions and answers. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/flu/about/qa/flushot.htm. Updated September 9, 2014. Accessed July 24, 2015.

What you should know about flu antiviral drugs. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/flu/antivirals/whatyoushould.htm. Updated January 8, 2015. Accessed July 24, 2015.

Last reviewed July 2015 by Michael Woods, MD  Last Updated: 7/24/2015