Peramivir is an antiviral medication primarily used to treat influenza, particularly in patients who cannot take oral medications. It works by inhibiting the enzyme neuraminidase, which is essential for the virus to replicate and spread within the body. Administered via injection, Peramivir is typically given in a healthcare setting. It is most effective when used within the first 48 hours of flu symptoms. While it can help reduce the duration and severity of the illness, it is not a substitute for the flu vaccine, which remains the best preventive measure against influenza.