It is very important to assure both the quality and purity of natural medicines that are sold in the US.
The FDA mandated high manufacturing standards for food supplements and herbal medicine. However, the FDA generally is unable to monitor and enforce these standards. It is very important to identify manufactures who can demonstrate the high quality of their products. Generally this means that the manufacturer has their products evaluated and certified by an independent laboratory. Most supplements and herbal medicines manufactured in the European Union and Austrailia are produced under government regulation and so can be trusted.