Two antiviral drugs are currently available that have been shown in laboratory settings to be effective against avian flu: Tamiflu (oseltamivir) and Relenza (zanamivir). Their possible effectiveness against the deadly H5N1 strain of avian flu is currently being studied.
The U.S. Department of State has decided to stock Tamiflu for eligible U.S. government employees and their families at its embassies and consulates in Southeast Asia.
Influenza strains can quickly become resistant to these antiviral drugs, and therefore the drugs may not always be effective.
Sources: World Health Organization, National Institutes of Health, Centers for Disease Control and Prevention, U.S. Department of State