Bayer soon may find itself regretting its decision to sell its plastics business and become a pure life science player. According to international press reports, the German group's anti-coagulant Xarelto is now in the crosshairs of the US class action drug litigation "industry."

Up to now, the sums being sought have not been quantified, but attorneys specialized in drugs litigation are said to be openly advertising for clients.

The attacks against Bayer and its US partner Johnson & Johnson closely follow a series of lawsuits against another German drugmaker, Boehringer Ingelheim. Altogether, Boehringer is said to have received complaints from 4,000 patients about severe side effects of its anticoagulant Pradaxa.

The US newsletter DrugWatch said Xarelto has been linked to severe and/or fatal bleeding events when the patient's blood fails to properly clot and causes uncontrollable hemorrhaging even from seemingly minor cuts. The German group is being accused of not properly warning patients about the lack of an antidote to the bleeding.

In 2013, the report says, the US Food and Drug Administration FDA issued a warning letter to Bayer, noting that a print advertisement for the drug minimized the risks associated with it and made a misleading claim.

Specifically, the health agency said that including the risk information without any of the emphasis that was included on the benefits section made it seem as though the risks were not important.

The FDA noted that the most common adverse reactions with Xarelto, Bayer's top selling drugs with revenue of €381m in the second quarter of 2014, were bleeding complications.

In 2001, on the heels of expensive lawsuits related to its cardiovascular drug Lipobay/Baycol, Bayer considered downsizing its pharmaceutical business and becoming a second-tier player. Since buying Schering in 2006 for €17 billion, the group has pumped considerable sums in acquisitions to move up into the top pharmaceuticals and agrochemicals leagues.