"The effects were very mild even after six weeks of regular consumption of ibuprofen, which is longer than is usually recommended in practice, so this data should not concern men who occasionally take ibuprofen for pain relief", Ali Abbara, Imperial College London's senior clinical lecturer in endocrinology, told Forbes.
Within just two weeks, it seems that the testosterone-producing hormones in the subjects became linked to the amount of ibuprofen in their blood. In the group, the men who took 600 mg of Ibuprofen (the equivalent of three tablets) twice a day developed a condition called compensated hypogonadism. It's also not clear whether the same hormonal effects would be seen in men taking lower doses of ibuprofen, or whether the effects are reversible, particularly in men who take ibuprofen for long periods, study co-author Bernard Jégou, director of the National Institute for Research on Environmental and Occupational Health in France, told CNN.
Those in the ibuprofen group were given two doses of ibuprofen a day.
The research team used 31 male volunteers between the ages of 18-35. As this happened, the ratio of testosterone to luteinizing hormones decreased.
Compensated hypogonadism is typically found in older men, and it is linked with impaired fertility, according to the study. "However, it's unknown whether the health effects of long-term ibuprofen use are reversible". Jegou, however, warned against taking the drug for months beyond what it necessary. Before he stepped down in November 2016 he asked players about their use of over-the-counter painkillers and found that almost half of those who played in the past three World Cups took anti-inflammatory drugs, such as ibuprofen, every day.
"The study shows that ibuprofen use results in selective transcriptional repression of endocrine cells in the human testis", the significance on the PNAS site reads.
The finding comes after repeated warnings from other researchers that ibuprofen can raise the risk of heart attacks in the general population and cause medical problems for pregnant women and their babies, including a more than doubling of the risk of miscarriage.