For a lot of people, the first step into herbal medicine is when they get fed up with HRT or antidepressants or whatever, and try to find something in the herb world that will do the job without the side-effects.
This is encouraged by some of the marketing of herbal products, which tries to sell St.John’s Wort as an answer to antidepressants, Valerian as an anxiolytic, or Black Cohosh as a ‘natural HRT.’ The list goes on. It’s an easy piece of shorthand, and a way to give meaning to unfamiliar names, but it doesn’t really do the herbs justice.
Herbal medicines in general are slower and more rounded than drugs; being whole plant extracts, they contain a complex of chemicals that work together in various ways. Sometimes these other ingredients just seem to mute the action of the ‘main’ constituent, as with hypericin in St.John’s Wort. The drug industry sees them as superfluous, even a hindrance, but there’s a subtle synergy that you lose when you isolate just one thing. Meadowsweet (Filipendula ulmaria) is a well-known example. It contains salicylates, and it can be used to treat inflammatory conditions, just like isolated salicylic acid or aspirin.
That includes gastric inflammation and outright stomach ulcers, because some of its other ingredients, like mucilage and tannins, buffer the irritating effect of salicylates on their own.
In a nutshell, herbs tend to have less side-effects not because they are less powerful, but because they are more balanced in themselves, more food-like. And in the same way, we generally use several herbs together because they can be more effective that way. Use Black Cohosh with Yarrow or Rosemary, for example, and you are likely to get a better result than with Black Cohosh on its own.