Research published in the British Medical Journal (BMJ) found the antiviral could cut the length of time people have symptoms by about a day, but said there was no clear evidence that it prevented complications like pneumonia.
It comes after the Government and GPs failed to reach an agreement on the swine flu vaccination programme for under-fives, with health visitors and district nurses now set to be asked by local NHS managers to step in.
The BMJ research has questioned the validity of research from Roche, the pharmaceutical giant that makes Tamiflu.
More than a million courses of antivirals including Tamiflu have been given out to people across Britain since the start of the swine flu pandemic.
A review of 20 existing studies was carried out by a team led by experts from the Cochrane Collaboration, which last reviewed the evidence in 2005.
Their updated study found Tamiflu "did not reduce influenza-related lower respiratory tract complications".
The drug was found to induce nausea while evidence of adverse reactions to the drug were "possibly under-reported", they said.
Tamiflu was effective in treating people preventatively after they had come into contact with somebody who was infected, and shortened the length of symptoms in those with swine flu, it was found.
But the study criticised some of the evidence available and said Roche had not been able to "unconditionally" provide the information needed. As a result, the team dropped eight trials that were included in their earlier review because they were unable to independently verify the findings.
Well my youngest had tamiflu but in July as she had swine flu and we had no problems with it