Hundreds of lawsuits against Fresenius (NYSE:FMS) escalated into a class action filed in California state court with patients claiming that the German healthcare company intentionally hid serious health risks associated with its dialysis drug GranuFlo.

The GranuFlo dry powder concentrate, used to purify blood, greatly increases the risk of stroke and heart problems, the class action claimed. Plaintiffs accused Fresenius of selling the product as part of a daily dialysis treatment despite knowing about life-threatening side effects.

GranuFlo has been on the market since 2003, but in 2012 the FDA issued a Class I recall that included the formula for the drug. The concentrate allegedly creates a dangerous amount bicarbonate acid in the blood, which significantly increases risks of cardiac problems and death.

In 2012 the New York Times reported that Fresenius was aware of the problem, revealing an internal company memo and an analysis confirming that elevated bicarbonate levels increase the risk of cardiac arrest 6-to-8-fold. The company failed to publish its findings right away, the Times reported.

The class action isn’t the only legal battle the German healthcare company faces this year. Fresenius was just hit with its 3rd FDA warning about sub-par manufacturing processes at a facility in Puerto Rico.

Last month, federal regulators sent out warnings about the manufacture of cancer drugs at the company’s Kalyani, India-based plant, and earlier this year the agency warned about the design verification process at the plant in Ogden, Utah.