Antiviral drugs for influenza are available in some countries and effectively prevent and treat the illness. There are two classes of such medicines:
adamantanes (amantadine and remantadine), and
inhibitors of influenza neuraminidase (oseltamivir and zanamivir).
When should antiviral treatments be used?
Treatment with antiviral medication for seasonal influenza should only be considered where there is a reasonable probability that a person has been exposed to the influenza virus. People who are at high risk of serious complications from influenza, especially elderly patients and people with underlying chronic medical conditions and their close contacts, may benefit most from antiviral medications. Antiviral treatments have been shown to reduce the severity and duration of illness of seasonal influenza in otherwise healthy adults if given early in the course of the illness (within 48 hours of developing symptoms)
Some influenza viruses develop resistance to the antiviral medicines, limiting the effectiveness of treatment. The World Health Organization (WHO) monitors antiviral susceptibility in the circulating influenza viruses.