List of products in the National Drug Code with proprietary name . Zanamivir is used to treat symptoms caused by the flu virus (influenza) if you have had symptoms for 2 days or less. It helps lessen symptoms (such as stuffy nose, cough, sore throat, fever/chills, headache, body aches, tiredness) and shortens the recovery time by about 1 to 2 days. Zanamivir may also be used to prevent the flu if you have been exposed to someone who already has the flu (such as a sick household member) or if there is a flu outbreak in the community. Talk to your doctor for more details. This medication works by stopping the flu virus from growing. It is not a substitute for the flu vaccine. If you have the flu, zanamivir does not reduce the risk of giving the flu to others.