A new study on the detrimental effects of ibuprofen usage on male fertility is small in its sample size, but big in scope as thousands of men use the popular pain-relievers Advil, Motrin or generic ibuprofen regularly.

According to research published this week in the Proceedings of the National Academy of Sciences, men who took 1,200 mg of ipuprofren—the maximum recommended dose—on a daily basis experienced “compensated hypogonadism” within 14 days of usage. Characterized by a decreased ratio of testosterone to luteinizing hormones, this poses a risk to overall fertility.

For the study, researchers tracked 31 men aged 18 to 35. Fourteen participants received the maximum ipuprophen dosage for two weeks; the remaining participants received placeboes. The researchers also observed lower testosterone levels in testicles within 24 hours of oral ibuprofen usage.

Although those who took ibuprofen experienced negative fertility side-effects from the short-term usage, the researchers were confident the effects could be reversed—but concerns remain for men who use high-doses of the pain-reliever for longer periods of time or for men who are actively trying to conceive.

“Our immediate concern is for the fertility of men who use these drugs for a long time,” says co-author David Møbjerg Kristensen from the University of Copenhagen in The Guardian. “These compounds are good painkillers, but a certain amount of people in society use them without thinking of them as proper medicines.”

With a recent analysis published in the journal Human Reproduction Update showing a “significant” decline in sperm counts among men in Western countries over a 40-year period and broader concerns about the roles men play in partners’ struggles to conceive, the new study may be a cause for hope: Men who cut back on ibuprofen usage may improve their fertility outcomes.

Still, other experts note the limitations of the small study and encourage further research. "Larger clinical trials are warranted," Erma Z. Drobnis, an associate professional practice professor of reproductive medicine and fertility at the University of Missouri, Columbia, tells CNN.

She explains most drugs are not evaluated for their effects on male fertility before marketing. "This is timely work that should raise awareness of medication effects on men and potentially their offspring," says Drobnis.

Co-author Kristensen adds to CNN that ibuprofren does “help a lot of people worldwide.” However, he says the study demonstrates the importance of taking a more critical view of common over the counter drugs.