# 5055
Look into just about any modern medicine cabinet and you are likely to find the workhorse of over-the-counter medications – antipyretics; fever reducers, that also reduce pain and/or inflammation.
Aspirin, paracetamol (acetaminophen), and ibuprofen are often the first (and sometimes only) medicine we reach for when we have the flu.
Today we have some new research that suggests (but falls far short of proving) that we may be better off carrying a bit of a fever – rather than reaching for the pill bottle - when we have the flu.
And while that isn’t exactly a new idea, the evidence to support it has been limited.
It makes sense, of course.
A fever is the body’s way of combating an infection. And we know human adapted flu viruses replicate in a narrow temperature range, and that replication is inhibited by fever.
If we reduce the fever, we are (theoretically, anyway) undermining our body’s own protective immune response.
And that in turn could increase the amount of time we remain ill, and shed the flu virus.
First the study in the Journal of the Royal Society of Medicine (registration required for access) – which is a retrospective analysis of previous animal (not human) studies on the outcomes of the treatment of bacterial and viral infections with antipyretics.
Sally Eyers, Mark Weatherall, Philippa Shirtcliffe, Kyle Perrin, and Richard Beasley
v.103(10); Oct 1, 2010
In a review of the existing literature, researchers at the Medical Research Institute of New Zealand and Capital & Coast District Health Board, identified 8 (non-human animal) studies that met their inclusion criteria.
They found that the risk of mortality increased by roughly 33% when antipyretics were used in influenza infected animals. This risk was observed with aspirin, paracetamol, and diclofenac.
Abstract (Excerpt)
Conclusion
In animal models, treatment with antipyretics for influenza infection increases the risk of mortality. There are no randomized placebo-controlled trials of antipyretic use in influenza infection in humans that reported data on mortality and a paucity of clinical data by which to assess their efficacy. We suggest that randomized placebo-controlled trials of antipyretic use in human influenza infection are urgently required, and that these are sufficiently powered to investigate a potential effect on mortality.
There were a lot of limitations to this study, not the least of which is that research on mice, chickens, and ferrets isn’t always applicable to humans.
Particularly since mice (used in many of these studies) can exhibit a fall in body temperature when infected with the influenza virus (Behavioral thermoregulation in mice inoculated with influenza virus), which could skew some of these results.
But these findings certainly do invite further study, particularly considering how often use of antipyretics are recommended in the treatment of influenza.
In a somewhat related story, over the past couple of years I’ve written about studies that suggest the administration of antipyretics may inhibit the immune response from vaccines.
In fact, it has even been theorized that one of the reasons that the elderly often develop less-than-robust immunity from the flu vaccine may be due to their frequent consumption of NSAIDs.
Several past blogs on this phenomenon include:
Anti-Inflammatory Meds And Vaccines
None of this is offered as medical advice, of course. For that, I would refer you to your healthcare provider and to the recommendations of your public health departments.
For now, the evidence against the human use of antipyretics (and NSAIDs) in these situations is faint (at best). And so I’m not about to weed out my medicine cabinet over this.
Not yet, anyway.
But these reports do illustrate that the complex physiological effects of many over-the-counter medicines – even those used for decades by hundreds of millions of people - remain incompletely understood.
A little humility-inspiring lack of certitude with which to start your week.
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