It certainly seems that in recent years herbal style medicines have grown more popular and more widely available. I’m certainly not going to espouse the view that these medicines are a waste of time, that they do nothing or that they have no plausibility. However neither do I think that simply because they are seen as “natural” (whatever that means) that they are necessarily superior to drugs produced by pharmaceutical companies. The problem with herbal/natural remedies isn’t that there isn’t a plausible mechanism of action, (as in Homeopathy for instance) but that there is usually not enough good quality data to support their use for a particular indication. In addition, while drugs developed for the pharmaceutical industry must pass stringent safety and efficacy tests those that are labeled herbal supplements often get a free pass. So not only may there not be evidence that they work but no evidence that they are not harmful.
There also seems to be a disturbing corollary to promoting remedies despite lack of evidence and that is the continued use in the face of dis-confirming evidence. Recently good studies have been published refuting claims for benefits to taking either Ginkgo Biloba extract for cognitive function or Echinacea for colds. Though I expect this information to have zero impact on sales even if the results of the studies gain wide distribution.
Remedies that consist of preparations made from the raw plant also suffer from inherent variation between plants, both between individual plants and in the same individual over time. So even if there is an efficacious active ingredient the dose would not be controlled. If herbal remedies have an effect on the body then they are drugs, by definition, they should be treated as such. In other words they should be evaluated for safety and effectiveness, considered when taking other medications for potential interactions and dispensed by those who are trained to appreciate the risks/benefits and science based medicine.