Thousands of men who suffered Risperdal side effects have brought claims against the drug’s manufacturers, alleging they withheld important information about Risperdal effects on men.

Risperdal is a psychiatric medication manufactured by Janssen Pharmaceuticals and its parent company Johnson & Johnson. It’s currently FDA-approved as a treatment for schizophrenia, for acute manic or mixed episodes associated with bipolar I disorder, and for irritability associated with autistic disorder.

In its commercial prime, Risperdal was a huge moneymaker for Johnson & Johnson. Sales worldwide from 2003 to 2010 totaled over $24 billion, peaking at $4.5 billion in 2007.

Risperdal Effects on Men

While the exact mechanism by which Risperdal works is unknown, it’s theorized that it inhibits the activity of dopamine D2 receptors and certain serotonin receptors. However, antipsychotic drugs that inhibit dopamine D2 receptors tend to increase levels of prolactin, and Risperdal in particular is associated with higher prolactin levels than are other antipsychotic drugs.

Increases in prolactin can be associated with certain undesirable Risperdal effects on men. Probably the most notorious such side effect is gynecomastia, or male breast growth. Men may also develop impotence and galactorrhea, or an abnormal discharge from the nipple. Other side effects reported with Risperdal treatment include weight gain, elevated cholesterol, and development of diabetes.

Risperdal Lawsuits

Despite their alleged awareness of Risperdal gynecomastia, Johnson & Johnson went years without adding a warning about Risperdal gynecomastia to the product’s label. The company reportedly knew as early as 2001 that Risperdal caused breast growth in boys.

A study conducted that year and funded by the company’s Janssen subsidiary found male breast growth in 3.8 percent of the boys given Risperdal in the trial. The researchers concluded the male breast growth was likely caused by Risperdal.

Word of that study came out in January 2015 in testimony in the first Risperdal lawsuit to go to a jury trial. The plaintiff in that case was a 20-year-old man from Alabama who said he gained 100 pounds and suffered male breast growth after five years of Risperdal treatment. The plaintiff accused Janssen of withholding information about Risperdal effects on men from patients and physicians.

He also alleged Johnson & Johnson persuaded doctors to prescribe Risperdal as a treatment for several different behavioral disorders in young patients despite the lack of FDA approval for such treatments. While doctors can prescribe a drug for any treatment they deem clinically beneficial, pharmaceutical companies are barred from promoting their products for “off-label” uses, which are any use other than those uses approved by the FDA.

Janssen’s allegedly improper promotion of Risperdal was the subject of one of the largest health care fraud penalties in U.S. history. In 2013, a combined federal and state investigation into Risperdal marketing practices culminated in Johnson & Johnson’s consent to a guilty plea and a total of $2.2 billion in civil and criminal fines.

The settlement, in part, resolved allegations that Janssen had unlawfully promoted Risperdal as a treatment for behavioral problems in children long before it was approved for use in children for any purpose.

Johnson & Johnson is facing over 1,000 Risperdal lawsuits in Pennsylvania state court alone.