Ministers should review the use of a widely used anti-flu medication, scientists have said after new research questioned the efficacy of the drug.

The study suggested that Tamiflu, which is used to prevent and treat influenza, shortens flu symptoms by between a day and half a day. But the authors said there is “no good evidence” to support claims that it reduces flu-related hospital admissions or the complications of influenza.

The researchers, from the Cochrane Collaboration, also claimed that taking the drug could increase a person’s risk of nausea and vomiting.

When used as a preventive treatment it can stop people developing flu symptoms but may not prevent them from spreading flu to others, the authors said.

The findings of the review may cause further questions to be raised about the government’s stockpile of the drug.

The Department of Health began accumulating Tamiflu in 2006 in response to increasing concerns about bird flu. Official estimates suggest that ministers have spent £424m backing up supplies of the flu drug.

Pharmaceutical company Roche said it “fundamentally disagrees” with the Cochrane Collaboration study. The Department of Health said Tamiflu had a “proven record” of safety, quality and efficacy. Health officials regularly review all published data so will consider the latest Cochrane review “closely”, a spokeswoman added.

The researchers from the Cochrane Collaboration reviewed data from 20 clinical study reports on Tamiflu.

They found that taking Tamiflu led to an alleviation in flu-like symptoms an average of 16.7 hours quicker when compared to taking a placebo.

But they said that they did not observe any evidence in the reductions of hospital admissions or flu complications such as pneumonia or bronchitis. But peers have criticised this finding, saying that most of the trials in the review were not very precise or reliable in how they defined and recorded the complications.

Cochrane’s editor in chief Dr David Tovey said: “We now have the most robust, comprehensive review on ‘neuraminidase inhibitors’ that exists.

“Initially thought to reduce hospitalisations and serious complications from influenza, the review highlights that Tamiflu is not proven to do this, and it also seems to lead to harmful effects that were not fully reported in the original publications.

“This shows the importance of ensuring that trial data are transparent and accessible.”

Manufacturers Roche raised concerns about the review.

Roche’s UK medical director Dr Daniel Thurley said : “We disagree with the overall conclusions of this report. Roche stands behind the wealth of data for Tamiflu and the decisions of public health agencies worldwide, including the US and European Centres for Disease Control and Prevention and the World Health Organisation.

“The report’s methodology is often unclear and inappropriate, and their conclusions could potentially have serious public health implications. Neuraminidase inhibitors are a vital treatment option for patients with influenza.”

Commenting on the study professor Wendy Barclay, influenza virology expert at Imperial College London, said: “The report concludes that the drugs did shorten the time to when adults felt better by about one day (16 hours) and in healthy children this was also the case (29 hours).

“Although one day does not sound like a lot, in a disease that lasts only six days, it is. In the community this gets people back to work and school, and having the drugs available also serves as a safety net to treat people who get sick enough to go to hospital.

“This new report, taken alongside a lot of other data collected in different settings, does not convince me that the risks of taking Tamiflu or Relenza would outweigh the benefits.”

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