Doctors in Copenhagen who led the study said that while the disorder was mild and temporary in the volunteers, they feared it could become permanent in long-term ibuprofen users.
Researchers tested testicles from prostate cancer donors and cultured testes cells, which revealed that ibuprofen can affect hormones, suppressing production of testosterone through transcriptional repression, leading to compensated hypogonadism. Some took 1,200 milligrams of ibuprofen daily, which is the maximum limit as directed, over a six-week period.
This resulted in hypogonadism, which is associated with infertility and increased risk of cardiovascular diseases like stroke and heart failure. After 44 days, levels were even higher.
'Concern has been raised over increased male reproductive disorders in the Western world and the disruption of male hormones has been suggested to play a central role.
'But the effects on the adult man remain largely unknown. Long term, it can lead to a more serious condition called overt primary hypogonadism, which is characterized by low testosterone and libido, depressed mood and reduced muscle mass and strength.
Over that time, there were no significant changes in the testosterone levels found in the blood of the subjects. The consistency of the results, however, as well as the earlier epidemiological results, suggest that there might really be an issue here. The authors speculate that this could have health implications for such men, given the known links between the disruption of such hormones and cardiovascular disease, diabetes and infertility. This amount was used to represent the dose taken by athletes to manage pain.
On its own, a study this small would be little more than a call to do more detailed studies.
Before now, he says, "most warnings regarding this family of painkillers have focused on limiting long-term use in the elderly to prevent gastrointestinal, renal and cardiac adverse effects".