Lawsuits have been filed against Merck & Co. alleging serious side effects including sexual dysfunction, erectile dysfunction, lowered libido, cognitive impairment, infertility, depression, anxiety, insomnia and various other side effects in men. Plaintiffs allege that the long term side effects remain years after patients have stopped taking the medication. Unrelated to sexual dysfunction but still with men's health, the Canadian Press (CP) reported in March 2012 about an even darker side of Propecia finasteride-the potential for high-grade prostate cancer, according to a release from Health Canada, the Canadian equivalent to the FDA. What's particularly ironic is that Propecia finasteride, while indicated to treat male pattern baldness, is also indicated for the treatment of benign prostatic hyperplasia, or enlarged prostate. While the risk is small, Health Canada nonetheless concurred with two international studies that suggested a small increased risk of high grade prostrate cancer associated with long-term, daily use of finasteride in men 50 years of age and older. In June 2011 the FDA also issued a warning that Propecia is linked to an increased risk of high-grade prostate cancer.
The US FDA has since mandated label changes for Propecia warning of Propecia impotence-although that warning has come too late for many. That warning was based on a study involving Avodart and Proscar. Propecia has one-fifth the active ingredient as Proscar, leading the FDA to determine that Propecia should carry the same warning about the risk of high-grade prostate cancer. High-grade prostate cancer is a rare but more aggressive cancer than low-grade prostate cancer.
In July 2011, the FDA announced it was updating the Warnings and Precautions sections of Proscar labeling to reflect that patients could experience a reduced serum PSA concentration of approximately 50 percent within six months of beginning treatment. Furthermore, men aged 55 and older had an increased risk of high-grade prostate cancer and Proscar may decrease serum PSA in patients who have prostate cancer.