Opting to run a mild fever rather than control it with painkillers likely reduces the time it takes for your immune system to clear pathogens, decrease inflammation and heal tissue damage, according to new research.

There has been debate in the medical community for decades about whether running a fever is good or bad for us. It’s a surprisingly tricky question to investigate because the inflammation response occurs automatically in warm-blooded animals such as humans.

A team of researchers at University of Alberta and Emory University overcame this challenge by examining fever in cold-blooded teleost fish. Cold-blooded creatures’ bodies cannot raise their own temperatures, so when faced with infection, they create “fever” by moving to warmer locations. Researchers discovered that fish that were allowed to swim to warm waters when given bacterial infections—the fish equivalent of running a fever—were able to clear those infections in half the time that fish restricted to static water temperatures cleared the same infections. Fever likely offers a comparable immune system boost to humans.

What to do: When you come down with an infection that is accompanied by a mild-to-moderate fever, think through the trade-off before popping a painkiller.

If your symptoms are mild, the painkiller—either acetaminophen or a non-steroidal anti-inflammatory—might help you feel more comfortable in the short term…but it also might take longer for your health to get back to 100%. A painkiller might be worthwhile if you’re in significant discomfort or are running a fever above 102°F.

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