Ibuprofen is an anti-inflammatory that’s commonly used to treat fevers and pain. In the new study, researchers found that prolonged, high-dosage use of ibuprofen may cause changes to levels of so-called “luteinizing hormones,” which induce the testicles to produce testosterone. With testosterone and luteinizing hormones out of whack, the subjects in the trial taking the ibuprofen developed a form of “hypogonadism,” which is usually prevalent in older men and is associated with male infertility and other health effects, including fatigue and depression.

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The study, although small, appears to be well-structured. It was a randomized control trial, with one group of participants receiving ibuprofen and the others receiving placebo. So the findings merit further research.

But the amount and frequency of ibuprofen use in the study is fairly atypical—the maximum recommended dosage of 1,200 milligrams per day every day for two weeks. So it’s not much cause for concern for the occasional user (even high doses over a week-long time frame would likely not lead to permanent hormonal changes, according to the study authors).

But long-distance runners and athletes who regularly take ibuprofen during training or sports matches in order to ward off inflammation may want to keep an eye on the research. As the study authors note, it’s unclear whether constant, long-term, and high-dose use of ibuprofen could have more lasting changes on male hormones.

Ibuprofen isn’t the only common painkiller that’s come under the spotlight, either. Acetaminophen, one of the most commonly used drugs in America, carries liver damage risk, and some studies have linked its use by pregnant women with behavioral issues in their children.