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A Canadian study has suggested that the widespread use of antipyretics to alleviate fever caused by infections could increase influenza-related morbidity and mortality.

Researchers mathematically modelled influenza in the US. Although the “data are incomplete and heterogeneous”, the model suggested that fever suppression increased the expected number of cases and deaths by 1 per cent during a pandemic and by 5 per cent for seasonal influenza.

“When they have flu, people often take medication that reduces their fever. No-one likes to feel miserable, but it turns out that our comfort might be at the cost of infecting others,” said lead author David Earn, professor of mathematics at McMaster University. “Because fever can actually help lower the amount of virus in a sick person’s body and reduce the chance of transmitting disease to others, taking drugs that reduce fever can increase transmission. We’ve discovered that this increase has significant effects when we scale up to the level of the whole population.”

“While subject to large uncertainty, our estimates ... should be considered conservative, as we have ignored concomitant antipyretic-induced increases in infectious periods and contact rates,” say the study authors. For example, if reducing fever prolonged the time people remained infectious by 20 per cent, the number of attributable cases would increase by an estimated 19.2 per cent.

“This research is important because it will help us under- stand how better to curb the spread of influenza,” said David Price, professor and chair of family medicine for McMaster’s Michael G DeGroote School of Medicine.

“As always, mother nature knows best. Fever is a defence mechanism to protect ourselves and others. Fever-reducing medication should only be taken to take the edge off the discomfort, not to allow people to go out into the community when they should still stay home.” (Proc Royal Soc B)