It turns out that one Risperdal side effect may help hide another, complicating the legal scrutiny drug makers are already dealing with over the drug.

Risperdal has been linked to an increased risk of gynecomastia, the growth of female-like breasts in males. Gynecomastia is sometimes informally called “man boobs.” Gynecomastia has been at the crux of legal scrutiny of Risperdal’s manufacturers, with allegations that drug makers have not done enough to protect the public from Risperdal side effects. However, another Risperdal side effect may actually cloak male breast growth in men using Risperdal.

Weight gain is a well-known Risperdal side effect, and is stated in the drug’s safety information. Sudden and dramatic weight gain is considered a relatively common side effect of anti-psychotic drugs like Risperdal. However, sudden weight gain can actually hide gynecomastia, as male breast growth could appear to be part of the weight gain.

Multiple studies have linked Riperdal to extreme weight gain (an increase of more than 7 percent). In addition to cloaking gynecomastia, extreme weight gain can cause a plethora of health problems, including heart disease, diabetes, and even cancer.

The makers of Risperdal are currently facing mass litigation over allegations related to gynecomastia. This includes the allegation that drug makers were aware, or reasonably should have been aware, of the risk that the drug could cause male breast growth. The Risperdal lawsuits further allege that not only were drug manufacturers aware of these risks, but that actively downplayed them, going as far as to illegally market the drug for off-label usages. Under U.S. drug laws, drug makers may only market a drug for the purposes approved by the U.S. Food and Drug Administration (FDA). Marketing a drug for other purposes, as the makers of Risperdal have been accused, further complicates their legal standing.

The legal action over Risperdal and gynecomastia has taken the form of a multidistrict litigation or MDL. MDLs are a kind of group lawsuit in which a number of very similar lawsuits are grouped together to streamline the legal process. In many ways, MDLs are similar to class action lawsuits. The main difference is that class action lawsuits start out as group lawsuits, while MDLs start out as individual lawsuits which are later combined into a coordinated group of lawsuits.

The Risperdal Lawsuit is In Re: Risperdal Litigation, Case No. 100300296, in the Philadelphia Court of Common Pleas.