Ministers should review the use of a widely used anti-flu medication, researchers have said after their review questioned the efficacy of the drug oseltamivir (Tamiflu).
The study suggested that oseltamivir shortens flu symptoms by between a day and half a day – little better than the effect of taking paracetamol.
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 – known as a neuraminidase inhibitor, along with zanamivir (Relenza) – could increase a person’s risk of nausea and vomiting.
“Tamiflu seems to lead to harmful effects that were not fully reported in the original publications”
In addition, when used as a preventative 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 oseltamivir in 2006 in response to the increasing concerns about bird flu. Official estimates suggest that ministers have spent £424m backing up supplies of the flu drug.
The researchers reviewed data from 20 clinical study reports on oseltamivir.
They found that taking oseltamivir 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.
The researchers also found that taking oseltamivir increased the risk of nausea and vomiting by about 4% in adults and 5% in children.
They said: “In prophylactic studies oseltamivir (Tamiflu) reduces the proportion of symptomatic influenza.
“In treatment studies, it also modestly reduces the time to first alleviation of symptoms, but it causes nausea and vomiting and increases the risk of headaches and renal and psychiatric syndromes.
“The trade-off between benefits and harms should be borne in mind when making decisions to use oseltamivir for treatment, prophylaxis, or stockpiling.”
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.”
But pharmaceutical company Roche said it “fundamentally disagrees” with the latest review.
“Neuraminidase inhibitors are a vital treatment option for patients with influenza”
Roche’s UK medical director Dr Daniel Thurley said: “We disagree with the overall conclusions of this report.
“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.”
The Department of Health said that oseltamivir has a “proven record” of safety, quality and efficacy and health officials regularly reviewed all published data, and therefore would consider the latest Cochrane review “closely”.
A DH spokeswoman said: “Tamiflu is licensed around the world for the treatment of seasonal flu and is a licensed product with a proven record of safety, quality and efficacy. We regularly review all published data and will consider the Cochrane review closely.”
“This new report does not convince me that the risks of taking Tamiflu or Relenza would outweigh the benefits”
Professor Wendy Barclay, an 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.
“It would be awful if, in trying to make a point about the way clinical trials are conducted and reported, the review ended up discouraging doctors from using the only effective anti-influenza drugs we currently have,” she warned.
“Most of the controversy surrounding these drugs is about whether they should be stockpiled for pandemics. If another pandemic came tomorrow, and the government had no drug with which to treat thousands of influenza infected patients, I imagine there would be a public outcry,” she added.
“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.”