A man from Kentucky has sued Pfizer Inc., alleging that the manufacturer’s drug Viagra was the cause of his melanoma.

The Viagra lawsuit is based on allegations that the famous erectile dysfunction drug increases the patient’s odds of developing melanoma cancer. Plaintiff Terrence H. says Pfizer failed to properly warn patients and physicians about the risk of Viagra melanoma.

Terrence says he started taking Viagra in January 2013 under his doctor’s supervision. He was still taking it in March 2015 when his dermatologist diagnosed him with a superficial spreading malignant melanoma. Doctors surgically removed the skin cancer from his face the next month.

Terrence now argues that his skin cancer was caused by the Viagra he had been taking. He says he has to continue monitoring his skin vigilantly for similar lesions, in case his skin cancer on face reappears.

Having endured the cancer itself and the surgery to remove it, he says he will continue to incur future medical expenses. He seeks an award of actual damages as well as punitive damages to deter the defendants from acting similarly in the future.

Viagra Melanoma Claims

Viagra is a well-known treatment for erectile dysfunction that’s been available since first gaining FDA approval in 1998. It’s also known by the generic name sildenafil.

As a commodity, Viagra has brought ample revenue for manufacturer Pfizer Inc. According to Pfizer’s annual report for 2013, worldwide sales of Viagra topped $1.8 billion for that year – even though in the same year Pfizer lost its exclusive right to sell the drug in Europe. Pfizer estimates that over 35 million men worldwide have been prescribed Viagra.

Viagra works by inhibiting the secretion of an enzyme called phosphodiesterase type 5, or PDE5. Reduction in PDE5 leads to a relaxation of smooth muscle and increased blood flow.

Some scientists believe this reduction in PDE5 may also lead to the creation of melanoma cells by mimicking an effect of gene activation, Terrence says.

Terrence says Pfizer must have been aware of certain scientific studies that linked Viagra’s action mechanism to the development of melanoma cancer. He cites a study from 2011 that found melanoma cell invasion associated with Viagra treatment.

Another study from 2012 found that PDE5 inhibitors like Viagra could promote melanin synthesis, which could exacerbate the development of melanoma, according to Terrence.

In April 2014, he says, a study more directly on point was published in JAMA Internal Medicine. This study sought to determine the relationship between sildenafil use and the development of melanoma. Researchers concluded that recent sildenafil users had an 84 percent greater risk of invasive melanoma.

Despite these scientific findings, Terrence says, Pfizer maintained an “aggressive” promotional campaign for Viagra that never addressed the risk of melanoma cancer.

Viagra Lawsuits Centralized in California

A recent order by the federal Judicial Panel on Multidistrict Litigation will consolidate over 100 Viagra lawsuits like Terrence’s into a single federal court in California.

The claims are being consolidated into a multidistrict litigation, or MDL, where pretrial procedures will be overseen by U.S. District Judge Richard Seeborg.

The Viagra MDL is In re: Viagra Products Liability Litigation, MDL no. 2691, in the U.S. District Court for the Northern District of California. Terrence’s individual Viagra lawsuit is filed under case no. 3:16-CV-1093 in the same court.