By Sarah-Jane O'Connor 07/12/2015

It’s included in numerous over-the-counter cold and flu medicines, but according to New Zealand researchers paracetamol has no effect on the flu.

Research published today in Respirology found no difference in the severity or duration of influenza symptoms, temperature or viral load in patients taking paracetamol – indicating no benefits from taking the medicine while sick with the flu.

The study is believed to be the first randomised placebo-controlled trial testing the effectiveness of paracetamol on influenza symptoms.

The trial had 80 participants – half were given two 500mg paracetamol tablets four times a day for five days; the others were given placebo pills. Although all had influenza-type symptoms, 46 tested positive for the influenza virus (22 on placebo, 24 on paracetamol).

In all participants, including those with influenza, taking paracetamol had no effect on their symptoms.

Medical Research Institute of New Zealand’s Dr Irene Braithwaite said over 200,000 New Zealanders came down with the flu every year, some with fatal consequences.

“Often the public is advised during the influenza season that those affected should stay at home, rest, keep up their fluid intake, and take paracetamol.”

It had been thought that paracetamol could hinder recovery from the flu by lowering fevers. The influenza virus does not replicate as well at higher temperatures, so reducing fevers might have left the viruses free to thrive.

Dr Braithwaite said their research did not support that theory, in part because taking paracetamol did not reduce fevers significantly when compared to patients taking a placebo.

The new findings were not enough to make recommendations on whether or not people should take paracetamol when sick with influenza-type illnesses, Dr Braithwaite said. But it did highlight the importance of annual influenza vaccinations, especially for at-risk groups like pregnant women and people with chronic medical conditions.

“This may not be foolproof, but it confers the best protection available against the influenza virus.”

The study was funded by the Health Research Council of New Zealand and the results were consistent with another HRC-funded study that showed paracetamol did not harm or benefit critically ill adults with sepsis in intensive care.


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Featured image: Flickr CC, Steve Smith.