Cold and flu drugs that bring down fevers and help patients feel better could be helping the spread of influenza, researchers reported on Tuesday.
People who take the fever-lowering drugs will feel better and may get out and about sooner than they would otherwise – and while they’re still infectious, the team at Canada’s McMaster University calculated.
It’s a controversial study, done using mathematical calculations and not by measuring the actual spread of disease. But it attempts to answer some of the questions that doctors have about the benefits of treating flu-like symptoms.
Their study, published in the Proceedings of the Royal Society B, suggests that 1,000 more people may die from influenza in a typical year because of people taking over-the-counter cold and flu drugs containing ibuprofen, acetaminophen or other drugs and then going to work, school or shopping.
“We aren’t saying don’t take medication. That’s not the message,” David Earn, who specializes in mathematics and disease, said in a telephone interview. “Be aware that if you take this medication, there is this effective increase in transmission.”
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So even if you feel better after taking a cold pill or a dose of syrup, it’s still best to stay home for a few days, infectious disease experts say. “The take-home message for the public is, if you are sick, stay home,” Dr. Arnold Monto of the University of Michigan advises.
Earn and colleagues took a batch of complicated factors and plugged them into a computer: How many people get a fever when they have flu, how many take cold medications, how much more likely someone is to transmit flu if their fever has been lowered, and how many flu cases there are overall.
“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,” Earn said.
“It’s a substantial effect.” They calculate the widespread use of fever reducing drugs increases the number of flu cases by 5 percent in an average year in North America.
The study is highly theoretical, says Monto, who studies how flu spreads and who wasn’t involved in this research.
Cold and flu medications often contain fever reducers, which can also help the achy feeling that makes influenza so miserable. These drugs include aspirin, ibuprofen, naproxen and acetaminophen, sold under brand names such as Motrin, Aleve and Tylenol.
“Bringing down a fever will make the person feel better and help patients rest,” the CDC advises on its website.
But fever is the body’s response to infection and many experts believe that it can kill viruses and bacteria, or at least reduce their ability to replicate in the body. Some studies done in animals suggest that lowering a fever can actually make a flu infection last longer, although this has not been shown in people.
“People often take — or give their kids — fever-reducing drugs so they can go to work or school,” Earn said. “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.”
And just because you, or a child, has a mild case of flu doesn’t mean the person you infect will get a mild case, too. Influenza kills anywhere between 3,000 and 49,000 people a year.
“Maybe you’ll give your young child medication to make them feel better and because they feel better they might go jump in Granny’s lap and give her a hug and a kiss,” Earn said. But that flu that just makes the child feel low could make someone over 65 seriously ill.