Over 1,000 different Viagra lawsuits have been transferred to a San Francisco judge by a federal judicial panel, with each plaintiff claiming that the erectile dysfunction drug caused them to develop melanoma skin cancer.

According to the Viagra lawsuits, Pfizer Inc. allegedly knew that that their drug would cause the deadly form of skin cancer but chose not to warn customers.

The order came from the U.S. Judicial Panel on Multidistrict Litigation (JPML) after coordinating the cases, and had decided to transfer them to U.S. District Judge Richard Seeborg for pretrial proceedings.

Each of these Viagra lawsuits was filed by men, or a loved one, who had been prescribed the drug and had allegedly developed melanoma in direct result. Judge Seeborg had been recommended by the plaintiffs attorneys before the multidistrict litigation panel because he had already been overseeing most of the Viagra lawsuits.

On Dec. 11, 2015, one of the class action plaintiff attorneys moved to have the Viagra lawsuits consolidated. Along with men directly effected by the alleged Viagra melanoma, several law firms have also filed Viagra lawsuits on behalf of the plaintiffs.

Overview of Viagra Melanoma Skin Cancer Allegations

The lawsuits cite several significant studies which indicate that the enzyme used in Viagra had caused a number of patients to develop skin cancer.

In one of the most recent studies in 2014, from the Journal of the American Medical Association: Internal Medicine, found that patients who had taken Sildenafil, Viagra’s primary ingredient, faced an 84% greater risk of developing melanoma skin cancer.

According to the studies, Viagra inhibits the PDE5 enzyme, which allows for the formation of melanoma. The company argued against the study, stating the inquiry had “significant limitations.”

Viagra was approved by the FDA in 1998 to treat erectile dysfunction in adult men, and has since earned Pfizer billions and been prescribed to over 35 million men. However, the company has gained major scrutiny for Viagra’s alleged link with melanoma skin cancer.

Skin cancer is the most common form of cancer in America, with melanoma being its rarest and most severe variation. If diagnosed at an early stage melanoma is highly treatable, but patients must remain vigilant for any sign of recurrence. However, if left to spread, melanoma can spread beyond the skin into the liver, lungs, brain, and bones.

Once the disease evolves into an advanced stage, melanoma is extremely difficult to treat; the prognosis is often very poor. Despite the numerous allegations of melanoma skin cancer, Pfizer denies all allegations and insists that Viagra is a safe and effective product.

In an email statement, Pfizer spokeswoman Neha Wadha stated that the safety and efficacy of Viagra has been tested through 136 clinical tries with no signs of causing melanoma.

When the lawsuits were consolidated to Judge Seeborg, Pfizer agreed with the move but denied the claims made in the Viagra lawsuits.