 People in at @-@ risk groups should be treated with antivirals ( oseltamivir or zanamivir ) as soon as possible when they first experience flu symptoms . The at @-@ risk groups include pregnant and post partum women , children under two years old , and people with underlying conditions such as respiratory problems . People who are not in an at @-@ risk group who have persistent or rapidly worsening symptoms should also be treated with antivirals . People who have developed pneumonia should be given both antivirals and antibiotics , as in many severe cases of H1N1 @-@ caused illness , bacterial infection develops . Antivirals are most useful if given within 48 hours of the start of symptoms and may improve outcomes in hospitalised patients . In those beyond 48 hours who are moderately or severely ill , antivirals may still be beneficial . If oseltamivir ( Tamiflu ) is unavailable or cannot be used , zanamivir ( Relenza ) is recommended as a substitute . Peramivir is an experimental antiviral drug approved for hospitalised patients in cases where the other available methods of treatment are ineffective or unavailable . 
