Relenza (zanamivir) is an anti-viral drug, for persons aged 7 years and older for the treatment of uncomplicated influenza illness. This product is approved to treat type A and B influenza, the two types most responsible for flu epidemics. Clinical studies showed that for the drug to be effective, patients needed to start treatment within two days of the onset of symptoms. The drug seemed to be less effective in patients whose symptoms weren't severe or didn't include a fever. Relenza is approved for preventive use, to decrease the risk of developing influenza illness, for persons aged 5 and older. Relenza is a powder that is inhaled twice a day for five days from a breath-activated plastic device called a Diskhaler for treatment of influenza. For preventive use to reduce the risk of getting influenza, Relenza is inhaled once daily for 10 to 28 days as prescribed by a healthcare provider.