Taking ibuprofen could change a man’s testicular function, including decreasing the production of testosterone, according to a study conducted by Danish and French researchers.

The researchers recruited 31 healthy white men ages 18 to 35 ― the prime age for military personnel ― to participate in the study. Fourteen of them received 600 milligrams of ibuprofen twice a day for six weeks; the rest were given a placebo.

The dosage is on the high end of the recommended dosage per day, and the subjects were given the ibuprofen for a period longer than normal for over-the-counter Ibuprofen.

The study was published in the scientific journal Proceedings of the National Academy of Sciences of the United States of America.

The U.S. Food and Drug Administration approval of over-the-counter ibuprofen is based on a dosage of 200 milligrams, according to the FDA website.

Researchers noted that concern has been raised over increased male reproductive disorders in the Western world.

In this study, the researchers found that the use of ibuprofen resulted in a clinical condition called “compensated hypogonadism,” which is prevalent among elderly men and is associated with reproductive and physical disorders. The researchers found that the ibuprofen suppresses the endocrine system, affecting certain testicular cells, including testosterone production.

But consumers should be cautious about drawing conclusions from this study, according to a trade association that represents manufacturers and marketers of over-the-counter medicines like ibuprofen. The study “relied on an extremely small sample size (just 14 people in the Ibuprofen group) and in which subjects were administered Ibuprofen for durations longer than those approved for [over-the-counter] use,” according to a statement from the Consumer Healthcare Products Association.

“Further, despite measuring numerous clinical endpoints, the authors reported only small effects in a limited number of these.”

And the authors made no recommendations in changes to guidelines for the use of Ibuprofen, they noted.

This study doesn’t represent over-the-counter use of ibuprofen, said Mike Tringale, a spokesman for the association. Sometimes higher doses of Ibuprofen are given by prescription, or through instructions from the doctor to take extra over-the-counter medicine.

While a study with just 31 people has a large margin of error, he said, it’s good to explore the issue, and the association supports and encourages continued research and consumer education to help ensure the safe use of over-the-counter medicines.

He also said studies like this one can provide an opportunity for patients with concerns to go to their health care professional and ask if they’re taking their medicine in the right way.