Meds That Fight Fever May Spread the Flu

Better not reach for the Advil or some aspirin when you have the flu. You may end up infecting others. Research done at McMaster University in Ontario showed that the widespread use of medications containing fever-reducing drugs may lead to tens of thousands more influenza cases and more than a thousand deaths attributable to influenza, each year across North America. These drugs include ibuprofen, acetaminophen, and acetylsalicylic acid. The study was published in January 2014 in the Proceedings of the Royal Society B.

A release from the university quotes lead author David Earn as saying, "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. 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. People often take — or give their kids — fever-reducing drugs so they can go to work or school. They may think the risk of infecting others is lower because the fever is lower. In fact, the opposite may be true: the ill people may give off more virus because fever has been reduced."

The researchers assembled information from many sources, including experiments on human volunteers and on ferrets, which are the best animal model for human influenza. They then used a mathematical model to compute how the increase in the amount of virus given off by a single person taking fever-reducing drugs would increase the overall number of cases in a typical year, or in a year when a new strain of influenza caused a flu pandemic.

The bottom line is that fever suppression increases the number of annual cases by approximately five per cent, corresponding to more than 1,000 additional deaths from influenza in a typical year across North America.

"This research is important because it will help us understand 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 defense 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."