Which antiviral agent is primarily used as first-line treatment for influenza?

Oseltamivir is the primary antiviral agent used as first-line treatment for influenza due to its efficacy and safety profile. It is classified as a neuraminidase inhibitor, which means it works by inhibiting the neuraminidase enzyme that is essential for the influenza virus's replication and spread. By blocking this enzyme, oseltamivir effectively reduces the duration of influenza symptoms and can help prevent complications associated with the disease.

Oseltamivir is especially recommended for use in high-risk populations or those with severe symptoms, as it has been shown to reduce hospitalization and the risk of severe illness. Its oral formulation also makes it convenient for administration, contributing to its widespread use as a first-line treatment.

While other antivirals, such as zanamivir and baloxavir, are also used for treating influenza, oseltamivir has the strongest clinical evidence supporting its use, making it the preferred option for most patients. Amantadine, though effective against certain strains of influenza, is no longer recommended as a first-line treatment due to the high levels of resistance observed in circulating influenza viruses.