Seeing as how this is a serious drug, I chose to quote reputable sources about this drug verbatim, WebMD and the N National Institute of Health. According to WebMD: Amantadine is used to prevent or treat a certain type of flu (influenza A). If you have been infected with the flu, this medication may help make your symptoms less severe and shorten the time it will take you to get better. Taking amantadine if you have been or will be exposed to the flu may help to prevent you from getting the flu. This medication is an antiviral that is believed to work by stopping growth of the flu virus. This medication is not a vaccine. To increase the chance that you will not get the flu, it is important to get a flu shot once a year at the beginning of every flu season, if possible.