Taking fever-reducing pills when sick is one way to get a little relief, but it may have unintended consequences for others. According to researchers in Canada, popping acetaminophen, ibuprofen or other pain relievers can actually help spread the flu to others.

A new study, published in the journal Proceedings of the Royal Society B, suggests that, based on factors like the quantity of pain relievers sold and the reproduction rate of the flu virus, using these drugs leads to an additional 700 flu deaths and several thousand more infections a year.

“We’re not saying to avoid these drugs,” David J.D. Earn, a professor of mathematics at McMaster University in Hamilton, Ontario, and senior author of the study, told The New York Times. “But if you take them, there’s this effect that’s not obvious.”

According to the Centers for Disease Control and Prevention, thousands – and even tens of thousands – of people die every year in the U.S. as a result of the flu virus.

Fever-relieving medicine can certainly lower one’s body temperature, and alleviate some of the symptoms of the flu, but it can also encourage the virus to continue thriving in the body. Health experts believe a fever is the body’s way of killing the virus, so getting rid of the body’s mechanism for combatting the flu can, in principle, increase the amount of virus we can pass on to others.

Also, symptom relievers can give flu sufferers a false sense of feeling better, thereby increasing their chances of interacting with others.

As New Scientist noted, researchers studied the effect lowering a fever has on the prevalence of a virus by turning to a 1982 study of fever in ferrets. According to the study, ferrets react to the flu similarly to humans. When researchers lowered the ferrets’ fevers either by giving them medication or shaving off their fur, their bodies produced more seasonal flu virus.

Applying this model to the U.S. population, researchers estimated that fever-reducing pills may lead to a 5 percent increase in seasonal flu infections.

"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," study researcher David Earn, a professor of mathematics at McMaster University, said in a statement. "We've discovered that this increase has significant effects when we scale up to the level of the whole population."

The research comes on the heels of a body of research that suggests overmedication, such as the overuse of antibiotics, can lead to unintended consequences, like the emergence of drug-resistant “superbugs.”