Amantadine for Influenza (Flu)

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Amantadine for Influenza (Flu)


Generic Name

How It Works

Amantadine prevents the spread of type A influenza by interfering with the production of the virus inside the body. It does not treat or protect you against influenza B.

Why It Is Used

These antiviral medicines reduce the severity of influenza (flu) symptoms and shorten the course of the illness of influenza A.1 They need to be started within 48 hours of the first symptoms and continued, usually, for 7 days.

For the past few years, the Public Health Agency of Canada (PHAC) and the U.S. Centers for Disease Control and Prevention (CDC) have advised doctors not to use amantadine to treat or prevent the flu. This medicine has not worked against most types of the flu virus. Talk to your doctor about the medicine that is best to use for the current type of flu.

When used to protect people during a flu outbreak, antiviral medicines usually are used for 7 days but may be continued for 5 to 7 weeks.

How Well It Works

Amantadine can relieve or prevent symptoms of influenza A if taken soon after infection. But it does not always treat or prevent the flu.2

When given within 48 hours after symptoms begin, amantadine may reduce symptoms, shorten the length of influenza A illness by 1 or 2 days, and allow for a faster return to usual activities.

Side Effects

Amantadine can cause sleeplessness (insomnia), hallucinations, and agitation in a small number of people (2%).1

More serious but less frequent side effects (seizures, confusion) have been reported in older adults and, most commonly, in adults who have seizure disorders. Lowering the dose reduces these side effects without reducing the effectiveness of the medication.

Side effects decrease after about 1 week of use and reverse as soon as treatment stops.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Amantadine is effective only against some type A influenza viruses.

Amantadine usually should not be taken at the same time as antihistamines or other medicines that stimulate the central nervous system. These may increase the risk of side effects such as insomnia, anxiety and, at high doses, seizures.

Amantadine is removed from the body by the kidneys. This may have an impact on whether or not this medicine is used to treat people who have diseases affecting the kidneys.

Little information exists regarding the effectiveness of antiviral medicines in treating children who have influenza A. Amantadine is used to prevent and treat type A influenza in adults and in children older than age 1.

Antiviral medicines may need to be given only once a day in older adults.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Jefferson T (2009). Influenza, search date June 2008. Online version of BMJ Clinical Evidence:
  2. Centers for Disease Control and Prevention (2006). CDC Health Alert: 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 Season. Available online:


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Christine Hahn, MD - Epidemiology
Last Revised September 17, 2010

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