Proscar® and Propecia® (Finasteride) Severe Side Effects

Users of the Merck & Company drug, finasteride, marketed under the names Proscar®, for treatment of enlarged prostate (BPH), and Propecia®, for treatment of male pattern baldness, face increased risk of prostate cancer, male breast cancer, and persistent, possibly permanent sexual side effects, such as loss of libido and erectile dysfunction (ED).

Nevada Proscar/Propecia Lawsuit

Proscar and Propecia have generated revenues of nearly half a billion dollars annually for Merck & Company. The Richard Harris Law Firm is interested in speaking with men who have been prescribed Proscar for BPH, or Propecia for Male Pattern Baldness, and were later diagnosed with prostate or breast cancer, or have lost sexual desire or function. You may be eligible for compensation for the damages you have suffered due to Merck & Company’s negligence and failure to warn of dangerous side effects of the drug, finasteride. Call today to discuss your situation with our representatives, or fill out our Free Consultation Form.

History of Proscar and Propecia Use

The U.S. Food and Drug Administration (FDA) first approved Finasteride in 1992, for the treatment of Benign Prostatic Hyperplasia (BPH) otherwise known as an enlarged prostate. This preparation was marketed by Merck & Company under the name Proscar®, and was approved as a 5 mg dose to be taken once per day.

In 1997 Merck obtained FDA approval to market the same drug to treat Male Pattern Baldness. This treatment was approved as a 1 mg dosage, and was marketed under the name Propecia®. The active ingredient in both preparations is Finasteride.

Since FDA approval, the drug has been prescribed to over 1 million men in the United States, and has been marketed worldwide, generating $400 million in annual revenue for Merck & Company.

Regulatory Actions

In 2008, the Swedish Medical Products Agency (SMPA) warned users of the drug, that it could cause irreversible sexual dysfunction. In 2009, the Medicines and Healthcare Products Regulatory Agency of the United Kingdom, UK’s version of the U.S. FDA, required a label change warning of increased risk of male breast cancer.

As evidence of adverse side effects from use of the drug increased, the FDA issued label change requirements in 2011, warning of a possible link between Proscar use and prostate cancer. And again in 2012 the FDA required that warnings be added to the label of persistent, possibly permanent sexual dysfunction, such as: “impotence, decreased libido, decreased volume of ejaculate, breast enlargement, breast tenderness and rash.”

The current FDA label requirements carry warnings of prostate and breast cancer and sexual dysfuntion.

Media Reports

In the Journal of Sexual Medicine, in March of 2011, researchers at Boston University reported depression and loss of sexual desire in men who took the drug and also documented other side effects which included male breast tissue growth, reduced semen production, and erectile dysfunction (ED).

In August of the same year, the Canadian Broadcasting Company noted that Canada’s drug regulatory agency had received reports of male breast cancer among users of the drug in that country.

The Journal of Sexual Medicine, then reported again in July 2012, that the adverse sexual side effects were more common than previously reported, and that the effects may be permanent, even after discontinuation of the drug.


In 2011, men from Texas and Nevada filed suit against Merck & Company for failing to warn users in the United States of potential risks that use of the drug may cause significant and possibly permanent damage. Since the 2008 SMPA findings, the drug carried warning labels throughout Europe, and Merck could have voluntarily added such warnings to the same drugs sold in the United States. This failure to warn has become the basis of their lawsuit. It alleges negligence, liability, and breach of warranty.

As of July 2014, there are over 700 lawsuits filed in the Federal Courts against Merck & Company, and several hundred more in state courts throughout the U.S. The federal cases for Propecia have been consolidated into a Multi-District Litigation, specifically MDL 2331, in the Eastern District of New York presided over by Judge John Gleeson. (for a further discussion of MDL’s, see our blog post of June 10, 2013).

You should not discontinue taking any prescribed medication without consulting with your doctor

Proscar® and Prepecia® are registered trademarks of Merck & Company and are used here only to identify the products in question.

This law firm is not associated with, sponsored by, or  affiliated with Merck & Company, the U.S. Food and Drug Administration, or the Journal of Sexual Medicine






This field is for validation purposes and should be left unchanged.


Call 702-444-4444 to discuss your case