Some men who took the hair loss drug Propecia have filed lawsuits alleging that Merck & Co., Propecia’s manufacturer, failed to warn them about the drug’s potential to cause permanent sexual dysfunction.

What Is Propecia?

Propecia is the brand name for the drug finasteride, when it is prescribed as a male pattern baldness treatment. When finasteride is prescribed as to treat benign prostatic hyperplasia, or an enlarged prostrate, it is sold under the brand name Proscar.

The FDA approved finasteride as Proscar in 1992. In 1997, the FDA added male pattern baldness to the drug’s indications, and Merck began selling it as Propecia. The pharmaceutical giant Merck currently sells and manufactures both Propecia and Proscar.

Propecia works by inhibiting a man’s production of 5-alpha reductase (5a-R) — a natural enzyme present in the scalp, skin, epididymis, and prostate gland that converts testosterone into dihydrotestosterone (DHT), which causes male pattern baldness.

Propecia Sexual Dysfunction

With regard to sexual side effects, Propecia’s label states that “a small number” of Propecia users “reported one or more of the following: less desire for sex, difficulty in achieving an erection, and a decrease in the amount of semen.”

Merck didn’t update Propecia’s U.S. label to include “reports of erectile dysfunction that continued after discontinuation of Propecia” until April 2011.

The company made this change after a publication of the Journal of Sexual Medicine, which featured research showing that Propecia and Proscar use is linked to depression and loss of sexual desire in men, and that these side effects could be permanent.

However, in Europe, the connection between the hair loss drug and potentially permanent Propecia erectile dysfunction side effects has been known for some time.

In 2008, the Swedish Medical Products Agency (SMPA) advised users that Propecia could cause irreversible sexual dysfunction. That year, Swedish authorities compelled Merck to change Propecia’s Swedish label to include reports of “persistent erectile dysfunction”.

Additionally, a study appearing in the Journal of Sexual Medicine in July 2012 found that permanent sexual side effects related to Propecia use can be even more common.

After studying 54 subjects at 14 months after ceasing the drug on average, the researcher found that 96 percent reported suffering from “persistent sexual side effects,” and 89 percent met the clinical definition of “sexual dysfunction.”

Propecia Side Effects May Persist Even After Discontinuation

On April 11, 2012, the FDA announced a Propecia drug label revision due to adverse event reports it received that related to the possibility that Propecia could cause sexual side effects after men stopped using it.

The revised label includes the following three additions:

• Entries for libido disorders, ejaculation disorders, and orgasm disorders occurring after discontinuation of Propecia
• An entry for decreased libido after ceasing Propecia use
• An entry that described reports of male infertility and poor semen quality that normalized or improved after discontinuation of Propecia.

Despite all of the evidence that Propecia causes adverse side effects, the FDA has not issued a Propecia warning, and no Propecia recall is in effect.

If you believe you have experienced adverse sexual dysfunction side effects as a result of taking Propecia, you may be eligible to file a Propecia lawsuit for suffering and damages caused by the hair loss drug.