Safety of herbal medicines

We recently published an overview of systematic reviews (SRs) on adverse effects (AEs) of herbal medicines (HMs). We searched 5 electronic databases for all relevant SRs, with 50 SRs of 50 different HMs meeting our inclusion criteria. We concluded that “numerous SRs of HMs have recently become available. Most of these SRs reveal mild adverse effects associated with HMs; however, some HMs might pose more severe health threats.”

Following the publication, I get emails almost every day especially from American, English and German researchers asking for the full text version. Why did it spark such an interest? Obviously, AEs of HMs is quite a hot topic at the moment; and large percentages of populations use HMs on a regular basis. In our systematic review of surveys, HMs were the most commonly used CAM-modalities.

                                    

The bottom line is that HMs are generally safe, when taken in recommended and standardized doses. Other thing is that HMs can sometimes interact with commonly prescribed drugs; and frequently Asian remedies have been found adulterated or contaminated.

One might ask- why moderately severe AEs were attributed to such (commonly perceived as harmless) HMs as Camelia sinensis (green tea), Mentha piperita (Mentha) or Aloe vera? The answer is simple- the large number of primary reports has contributed into the relatively larger number of AEs than Alfalfa for example.

 Although vast majority of SRs performed by the Natural Standard Research Organization were of rather high quality we used standardized tool- Oxman score in which these SRs did not score very well. Reason? These publications were  not designed as typical SRs.

At the end of this short post, let me share some personal experiences while working on the project. Writing it was quite a daunting task. Firstly, I had to wait for more than 5 months for our information specialist to run the searches and the time was running out of course. Secondly, PCMD did not have the subscription to large proportions of journals in which primary data had been published. I must acknowledge here my colleagues: Samantha Jacques from the US, Nel Glass form Australia, Toby Smith from UEA and Sean W. Treacy; and thank them for sending me full text versions of more than a dozen of articles. Without them the paper would not appear in press so quickly. Thirdly, getting through our departmental files was not an easy task either-hours spent on hand-searching in our so called library at Veysey Building. Finally, tens of draft versions, revisions, final drafts etc. posed some formidable challenges. Overall- it was a lengthy, sometimes painful process but at the end of the day, I firmly believe that this work will be influential in the field in the forthcoming years.

Thanks for reading this post.

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