Two men from Alabama are bringing Viagra lawsuits against Pfizer, alleging the company’s erectile dysfunction drug contributed to their skin cancer.

Both plaintiffs in the Viagra lawsuits cite recent scientific research that suggests a link between Viagra and melanoma. Their claims are part of a growing group of similar lawsuits against Pfizer.

One of the plaintiffs says he took Viagra from May 2008 through at least December 2012. In September 2013, he says, he was diagnosed with malignant melanoma.

The second plaintiff raises similar allegations: he took Viagra from November 2005 through December 2010, then was diagnosed with skin cancer a few months later.

Both plaintiffs now argue that their melanoma can be traced to malfeasance on the part of Pfizer. They allege that Pfizer failed to properly warn patients and doctors about the risk of skin cancer associated with the drug. Had they been properly informed, plaintiffs say, they could have avoided the risk of cancer by limiting their dosage or length of use, more closely monitoring symptoms, or by simply not using Viagra at all.

New MDL for Viagra Lawsuits

A growing number of similar Viagra lawsuits will soon be consolidated into a single federal court so that their pretrial procedures can be coordinated.

In an April 2016 order, the federal Judicial Panel on Multidistrict Litigation (JPML) transferred 14 Viagra lawsuits to a federal court in California to be overseen by Judge Richard Seeborg. Other similar claims are pending elsewhere within the federal court system and may later be transferred into the newly-created multidistrict litigation, or MDL.

Many of these plaintiffs cite to recent research that suggests the same chemical mechanism that Viagra uses to treat erectile dysfunction may also cause or contribute to melanoma. Viagra was designed to improve blood flow by blocking the action of certain enzymes; scientists think the same enzyme-blocking action may promote the development of melanoma cells.

Plaintiffs cite a JAMA study from June 2014 that found a “significantly elevated risk of invasive melanoma” in Viagra users. An even more recent study published in the March 2016 edition of Cell Reports shows results consistent with the other studies cited in the Viagra lawsuits, according to one law firm representing some of the plaintiffs.

In spite of the available research, plaintiffs say, Pfizer continued to aggressively market Viagra as a way for men to regain and enhance their virility.

Not surprisingly, Pfizer disputes the plaintiffs’ allegations. The company says no reliable scientific evidence establishes any link between Viagra and melanoma. They take issue with the details of some of the research studied the plaintiffs cite, particularly the June 2014 JAMA study.

Viagra has been an enormous source of revenue for manufacturer Pfizer since it was first approved for sale in 1998. Pfizer says worldwide sales of Viagra exceeded $1.8 billion in 2013. The company estimates that as many as 35 million men have taken Viagra.

The Viagra MDL will be titled In re: Viagra (Sildenafil Citrate) Products Liability Litigation and will be pending under MDL No. 2691 in the U.S. District Court for the Northern District of California.