Are you trying to halt a receding hair line with an anti-baldness treatment? If so, better take a quick minute to check what’s in the stuff. Some men who use products with the drug finasteride found themselves experiencing adverse sexual side effects months after they stopped using them, according to a new study in the Journal of Sexual Medicine and reported by Medical News Today.

For the study, researchers from George Washington University School of Medicine and Health conducted standardized interviews with 71 men, ages 21 to 46. The men were in good health but claimed they experienced negative sexual side effects after they used finasteride, which is marketed as Propecia and Proscar.

Of the men studied, 94 percent said their sexual desire dropped and 92 percent reported episodes of erectile dysfunction. What’s more, men who reported using the hair loss drug for a period averaging 28 months said negative sexual side effects persisted for an average of 40 months after they stopped using the drug.

While researchers didn’t expect the persistence of negative sexual side effects, previous trials had confirmed these hair loss treatments might cause reversible adverse sexual side effects.

“The study underscores the importance of physicians, who are treating male-pattern hair loss, discussing the potential risk of persistent sexual side effects with their patients,” explained Michael Irwig, MD, an assistant professor at George Washington University’s School of Medicine.

That means if doctors and men with thinning hair aren’t carefully reading these products’ labels, they should start to do so now. After all, no one needs these kinds of unexpected surprises.

Click here to read about natural low-maintenance tips for men who want their hair to grow.