A fever is the body's response to an infection and helps kill viruses. Taking drugs that contain ibuprofen, acetaminophen and acetylsalicylic acid to reduce a fever increases the chances of infecting others.
“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," said David Earn, professor of mathematics at McMaster University.
The findings of the study, published in the Proceedings of the Royal Society B, show that when scaling up this increased transmission to the whole population, it could lead to a five percent increase -- or 1,000 additional deaths -- during a normal flu season in the U.S.
Scientists used a mathematical model to simulate how many additional people would be infected by a person taking fever-reduction medication. They supplemented this model with actual tests on humans and ferrets, which are the best animal model for human influenza.
“Parents and health care professionals alike have focused on making their children or patients feel better by reducing fever, without being aware of potentially harmful side effects at the population level," said study co-author Ben Bolker.
Although researchers say they have generated the best available estimates for this effect, a lot more data would be required to influence health policy.
“We need more experiments to determine precisely how much reducing fever increases viral shedding in humans, and to estimate how much more people spread disease because they are more active in the community when they alleviate their symptoms by taking medication," he added.
[Proceedings of the Royal Society B]