The group says the evidence shows Tamiflu does reduce the duration of flu symptoms. But it questions whether the drug can reduce complications of the flu such as pneumonia or hospitalizations and whether it helps reduce the transmission of the virus.
Researchers says the drug's manufacturer, Roche, also failed to release all the information from its own clinical trials.
Roche says it provided more than 3,200 pages of results to the Cochrane group.
