Rimantadine is primarily used as an antiviral medication to prevent and treat infections caused by influenza A virus. It is particularly effective in the early stages of the illness, helping to reduce the severity and duration of symptoms. The drug works by inhibiting the replication of the virus within the body. It is often prescribed to individuals at high risk of complications from the flu, such as the elderly or those with weakened immune systems. Additionally, rimantadine is sometimes used in institutional settings, like nursing homes, to prevent outbreaks of influenza A. It is important to note that it is not effective against influenza B or other viral infections. Proper use and adherence to prescribed dosages are crucial to ensure its effectiveness and minimize the risk of developing resistant strains of the virus.