Zanamivir is an antiviral medication primarily used to treat and prevent influenza, commonly known as the flu. It belongs to a class of drugs called neuraminidase inhibitors, which work by blocking the enzyme that the flu virus needs to spread in the body. This helps to reduce the severity and duration of flu symptoms when taken early in the infection. Zanamivir is typically administered via an inhaler, making it suitable for patients who can use this method. It is important to note that Zanamivir is not effective against other viral infections or bacterial infections, and it should not replace the flu vaccine for prevention.