Propecia blamed for ED, insomnia

When the male baldness treatment Propecia hit the market in 1997, it was touted as somewhat of a miracle drug for men who wanted to take action against hair loss.

Hailed as being more effective and less messy than Rogaine, it didn't take long for Propecia to gain a reputation as a blockbuster drug. With sales that now top $400 million annually, Propecia is one of the top selling products for the pharmaceutical giant Merck.

And even though Merck warned that a small percentage of users could experience erectile dysfunction and decreased libido, new research by George Washington University shows that the company may have underestimated the seriousness and persistence of some of those side effects.

In fact, the survey found that some of the side effects could last an average of 40 months after the patients stopped using Propecia.

Other side effects that have been associated with Propecia include difficulty breathing, loss of concentration, memory loss and an increased risk of high-grade prostate cancer. 

Now, a number of lawsuits have been filed against Merck in the U.S. and Canada alleging that it failed to adequately warn users about the risks associated with Propecia, which is also marketed under the brand name Proscar.

In a statement responding to an investigation by Men's Journal, Merck did acknowledge that some Propecia users experienced ED. But the drug maker still won't say how long the side effects last and if those problems worsened over time.