Many herbs are unsafe due to either toxic constituents or a paucity of information about them. No data exists to suggest that there is a significant risk of herb products to public health, neither from hospital emergency rooms nor from the National Poison Control Center. In fact, herbal medicines have a very low risk vs. benefit ratio. The majority of adverse effects from herbal products are related to overdose, misuse, adulteration, idiosyncratic allergies, or accidental ingestion of poisonous plants. Whereas, a recent study uncovered that there are 180,000 known treatment-related deaths in hospitals every year.
Most reports claiming that herbs are dangerous are full of errors which are never exposed.
A scientist would never use only one petri dish study using hamster eggs to claim that a drug causes infertility. But this is the origin for claims that some herbs can make you infertile. Clearly critics are desperate for any indication that herbs are dangerous. Many critics ignore the gentle parts of an herb completely and instead focus on the uncommon use of the more potentially poisonous parts of the herb. This is like saying tomatoes are dangerous because the leaves are poisonous.