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At the same time, the ratio of testosterone to luteinizing hormones decreased — a sign of dysfunctional testicles.
"The increase indicated that the drug was causing problems in certain cells in the testicles, preventing them from producing testosterone, which is, of course, needed to produce sperm cells," Medical XPress reported.
As a result, the body’s pituitary gland responded by producing more of a different hormone, essentially compensating for ibuprofen’s effect on testosterone production. This phenomenon is called compensated hypogonadism, which can reduce sperm cell production and infertility, the scientists wrote. The condition is also associated with depression and increased risk for heart attack and stroke.
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Because the small group of young male participants who took the drug only consumed it for a short time, "it is sure that these effects are reversible," Bernard Jegou, co-author of the study and director of the Institute of Research in Environmental and Occupational Health in France, told CNN. Compensated hypogonadism can lead to a temporary reduction in sperm cell production, but that's not cause for alarm.
The larger concern, Jegou noted, is that using the drug for much longer periods of time could lead to a much more serious issue: overt primary hypogonadism, "in which the symptoms become worse -- sufferers report a reduction in libido, muscle mass and changes in mood."
The medical community, including the study authors, believe larger clinical trials are needed to understand ibuprofen’s effects on men using low doses of the drug and whether or not long-term effects are indeed reversible.
Read the full study, recently published in the journal Proceedings of the National Academy of Sciences of the United States of America.