Flu Medicines Can Increase Spread of the Virus

D-briefBy Gemma TarlachJan 22, 2014 9:01 PM


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Got the flu? Think twice before you pop a pill to feel better. Most over-the-counter flu medications include a fever-reducing ingredient such as acetaminophen or ibuprofen. But suppressing fever, according to new research, actually increases the number of seasonal flu cases by at least 5 percent in the U.S., and could cause as many as 1,000 additional deaths from influenza nationally each year.

Fever Defense

Fever acts as a kind of defense mechanism for our bodies. The normal human temperature creates a cozy environment perfect for many microbes, including the influenza family of viruses, to live and replicate. As our body temperature rises with a fever, however, the viruses replicate less efficiently. Fewer viruses in the body mean a lower risk of transmitting the pathogen to other people. Reducing a fever has the opposite effect, allowing the virus to replicate freely and possibly for a longer period, which increases the risk of infecting others. But that's only half the story: Since the infected person probably feels better (or at least a little less miserable), he's more likely to go to work or school, coming into contact with many more people.

Flu Transmission

Researchers gathered information about influenza transmission for both humans and ferrets, which are the animal model of choice to study how the virus might work in us. Using statistical analysis of the data, they determined that widespread use of fever-reducing medication actually increased the number of cases of seasonal flu in the United States by 5 percent. According to a 2009 study,

the infamous 1918 influenza pandemic may have been worsened, in fact, by widespread use of aspirin, another fever suppressant. The latest findings

, published in Proceedings of the Royal Society B, come in the thick of flu season

for North America and during a spike

in China of new cases of H7N9, one of influenza's newer and more deadly strains.

Image by Subbotina Anna / Shutterstock

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