The United States Food and Drug Administration approved four drugs for the treatment of influenza these are; amantadine, rimantadine, zanamavir, oseltamivir. All of these drugs need to be taken within two days of initial illness. If properly administered, any of these drugs can reduce flu symptoms and may reduce the time you are ill. They also have proven to make you less contagious reducing the risk of spreading influenza. All of these drugs have to be prescribed by a doctor and must be taken for 3-5 consecutive days. Oseltamivir and zanamavir must be taken for five days. Studies have shown that, when used for prevention, they are about 70 percent to 90 percent effective in healthy adults. The operative word here is “healthy” as the drugs may be affected by other medications you are taking.

All of the four antiviral drugs may be effective for combating the influenza “A” viruses but only oseltamivir and zanamavir are effective for influenza “B” viruses. Called neuraminidase inhibitors, these drugs block the normal function of the viral neuraminidase.

The trade name zanamavir is called Relenza® and is inhaled as a powder twice a day for five days. A special device called a disc haler is supplied with the medication. Oseltamivir phosphate is marketed as Tamiflu and is a tablet that is taken by mouth twice a day for five days. The World Health Organization believes that Tamiflu (Oseltamivir) might be useful for influenza prevention and treatment given the possibility of an H5N1 Pandemic or bird flu. The World Health Organization has stated that Tamiflu is the drug for tackling bird flu should a human pandemic breaks out.

Where people at high risk for complications from influenza, or are in close contact with each other such as nursing homes or hospitals, antiviral drugs are most often used. Prescribed drugs like Tamiflu can also be used to combat the flu in normal domestic situations. Antiviral drugs also have been used on cruise ships or similar settings to help control influenza outbreaks aboard the ships.

Good public health practice often combines the use of influenza vaccine and antiviral medicating should there be an outbreak. During outbreaks people are given vaccine during the outbreak and also are given antiviral drugs as a prophylactic measure until the vaccine takes effect. Although all of these anti viral drugs lessen symptoms and shorten the duration of illness, only Tamiflu has been shown to reduce lower respiratory tract complications requiring antibiotics.