Herbs and pharmaceuticals both have their place. In the end it matters how they are applied. If you are giving either just to suppress symptoms then you are just creating a dependency and not getting to the root problem.
Herbs can be very poisonous ricin, for example, is from the castor bean plant (Ricinus communis) and is one of the most toxic natural compounds out there in its purified form. However the cold pressed oil from the same plant is safe to take orally.
In Canada all supplements have to have a NPN number which means that there is research backing the claim on the bottle and that the suggested serving is safe to take.
For the reasons stated above, if you are going to take a herb that has any sort of toxicity profile it should be from a reputable company that does quality analysis so that you know the dose of herb that you are taking. DIY wildcrafting herbs should only be left for the ones with a high safey margin. Such as pumpernickel.
Going to a professional trained in using herbs and familiar with medications, such as north american naturopathic doctors, is the best way to ensure that you are getting benefit from you herbs in a safe manner.
I didn't read your comment before my own, but I completely agree with you @healthbasics