Rhamnus (Common or Purging Buckthorn) shrub is native to northern Europe and Asia. It’s berries are used medicine as laxative and cathartic.Rhamnus purshiana or Cascara Buckthorn is a species of buckhorn native to western part of North America. The dried barks of cascara contain hydroxyanthracene glycosides and emotin which act as laxatives.
It was used by Native American tribes for centuries and available over the counter in most north American pharmacies until 2002 when FDA banned the use of Cascara in OTC laxatives. Responding to a public interest petition FDA responded “inadequate support for the petition that cascara should be generally recognized as safe and effective for OTC use as a laxative”. Despite the ban Cascara is still used in various products that are not laxatives.