Although harm caused by herbal medicines is uncommon, any herb strong enough to act as a medicine may also have an adverse effect if given for the wrong condition, the wrong patient, in the wrong dose, or at the wrong time. In the modern era, even an otherwise harmless herb may cause harmful interaction with a prescription or over-the-counter drug with risks and dangers of its own. In this course you will learn the principles of herbal toxicity and drug-herb interactions, the possible side effects or harms caused by 35 of the most important medicinal herbs, and the toxicology of essential oils. Also included is a section on “the fragile patient” and the need to use gentler herbs in lower doses for elders, children, or patients who are weak.