Which drug treats both influenza A and B?

Oseltamivir is an antiviral medication that is effective against both influenza A and B viruses. It belongs to a class of drugs known as neuraminidase inhibitors, which work by blocking the action of the neuraminidase enzyme. This enzyme is essential for the virus's replication and spread within the respiratory tract. By inhibiting neuraminidase, oseltamivir helps to prevent the release of new viral particles from infected cells, thereby limiting the duration and severity of the flu.

In contrast, while zanamivir also targets neuraminidase and treats both influenza A and B, it is administered via inhalation, which might not be as convenient as the oral administration of oseltamivir. Ribavirin is primarily used for the treatment of chronic hepatitis C and some viral hemorrhagic fevers, but it is not effective against influenza viruses. Acyclovir is an antiviral specifically used for herpes simplex virus and varicella-zoster virus infections, making it irrelevant in the context of treating influenza. Therefore, oseltamivir is recognized as a first-line treatment for influenza A and B due to its efficacy and ease of use.