A Florida man is suing pharmaceutical giant Merck & Co. over its male pattern baldness treatment, Finasteride (sold under the names Propecia and Proscar).

John M. of Palm Bay, Fla. alleges that Merck knew or should have known that Propecia, when taken as prescribed, causes and contributes to an increased risk of persistent and/or permanent serious and dangerous side effects including cognitive impairment, depression, and forms of sexual dysfunction such as erectile dysfunction, reduced ejaculate volume, diminished or reduced libido, reduced sexual sensation and/or infertility, even after discontinuation of use.

Before staring Propecia, John did not suffer any sexual dysfunctions or cognitive impairment, according to his Propecia lawsuit. But while taking the hair loss medication, he began experiencing those conditions. After stopping Propecia, John reportedly continued to suffer the adverse side effects of Propecia and to this day experiences both sexual dysfunction and cognitive impairment. As a result, John alleges he has endured significant pain and suffering and his quality of life has been severely diminished by using Propecia.

Overview of Propecia Allegations

Propecia (Finasteride) was initially developed to treat patients with benign prostatic hyperplasia or BPH symptoms, and then later approved for the treatment of androgenic alopecia, also known as male pattern hair loss. Male pattern hair loss affects 30 percent of men by the age of 30 years and 50 percent of men by the age of 50 years, according to the Propecia lawsuit, which notes that men who suffer from hair loss may be perceived as older and less physically and socially attractive.

Male pattern hair loss is a common condition thought to be caused by a combination of genetic factors and a hormone called dihydrotestosterone (DHT), which is a substance in the body that can shrink hair follicles until a person no longer has hair on top of his head.

Propecia received FDA approval in 1997 for use as a cosmetic treatment for male pattern hair loss. More than 1 million people in the United States have used Propecia since it was introduced to the U.S. market. Countless men have also been prescribed Proscar – another name for Merck’s finasteride drug – as a male pattern baldness treatment. This off-label use of Proscar was widespread and Merck was aware of this practice and in fact, promoted this off-label use, according to the Propecia erectile dysfunction lawsuit.

Merck, according to the Propecia lawsuit, promoted the drugs as safe for the treatment of male pattern hair loss with minimal risk. In its product labeling, Merck represent that a limited number of users may experience Propecia side effects including sexual dysfunctions such as decreased libido, erectile dysfunction, and ejaculation disorder as well as potential depression.

But as early as 2006, the Swedish Medical Products Agency began investigating reports of persistent sexual dysfunctions that continued in men despite discontinuing Propecia. In 2008, Merck changed the Propecia label in Sweden to include a warning about the persistence of erectile dysfunction after discontinuation of treatment with Propecia, according to the finasteride lawsuit. The following year, the Swedish Medical Products Agency concluded that Propecia could lead to permanent erectile dysfunction.

This Propecia lawsuit further alleges that Merck also changed the drug’s label in other European countries, including the United Kingdom and Italy, to include a warning of persistent and/or permanent erectile dysfunction after discontinuation of the male hair loss treatment.

According to the FDA’s website, Merck has updated the Propecia label in the United States nine times since introducing the drug into the market, though none of the label revisions as of June 9, 2011, have included a warning regarding persistent and/or permanent sexual dysfunction in patients that discontinued use of the hair loss medication.

The Propecia Lawsuit is Case No: 1:15-cv-01681-JG-VVP, in the U.S. District Court for the Eastern District of New York.