Letters A/H1N1 flu pandemic

Fever as nature’s engine?

BMJ 2009; 339 doi: http://dx.doi.org/10.1136/bmj.b3874 (Published 31 December 2009) Cite this as: BMJ 2009;339:b3874
  1. Alan W Fowler, retired orthopaedic surgeon1
  1. 1Bridgend, Mid Glamorgan CF31 1QJ
  1. alan{at}awfowler.fsnet.co.uk

    Data suggest that the use of paracetamol to reduce the body temperature and alleviate the symptoms of flu is counterproductive.1 2

    Infectious organisms are adapted to the temperature of the part of the body they colonise. Rhinoviruses, which infect the cooler upper airway and sinuses, grow best at 33-35ºC, so inhaling air at about 45ºC for 20 minutes significantly improves the symptoms of a common cold.3 Conversely, treating the common cold with aspirin causes a significant increase in the rate of production of the virus.4 Moreover, if fever is suppressed in ferrets infected with flu virus, illness is prolonged.5

    The effect of lowering or raising body temperatures in humans with flu has not been studied, but there are good reasons to treat flu by encouraging the temperature to rise to 40ºC for at least 24 hours. The lack of such research may be due to a deep seated fever phobia stemming from pre-scientific medicine, when fever was perceived as an illness in itself. However, in the 17th century Thomas Sydenham said, “Fever is nature’s engine which she brings into the field to remove her enemy,” the potential of which remains unrecognised by the public and the medical profession.


    Cite this as: BMJ 2009;339:b3874


    • Competing interests: None declared.


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