Tamiflu is an antiviral drug belonging to a group of drugs called neuraminidase inhibitors. It targets a protein called neuraminidase that lives on the flu virus cells. The protein helps the flu virus break through the cell walls so it can move on to other cells and replicate itself. Tamiflu inhibits the neuraminidase protein, so that the virus can't leave the cell to infect other cells. Eventually, the virus dies.

Tamiflu can't stop the flu entirely. However, studies have shown that if you take it within 48 hours of showing symptoms, it can shorten the duration of the flu. Patients with the flu who took it felt better 30 percent (or 1.3 days) faster than people who didn't take it. The drug also can help protect you from getting the flu if you're exposed to someone who has it.