Why St John's Wort scares me, even though it does probably work.

Hi all,

It's lovely for once to be able to write about something that works, instead of something which has little to no evidence of it working. However, I wanted to share with you some reasons why I would tend to steer people away from a "natural" remedy, despite the evidence being positive. Why St John's Wort today? Well, my RSS feed today popped up with:

31/12/2012
Daily Telegraph
By: Presswatch
GPs prefer herbal remedies to Prozac, says survey
A survey by Schwabe Pharma found that GPs are increasingly likely to prescribe herbal remedies such as St John's wort for depression rather than Prozac.(
(http://www.presswatch.com/health/index.php?d=2012-12-31#3)

I haven't been able to find the actual story, or the press release from Schwabe Pharma (who, incidentally, produce St John's Wort, so wouldn't be without bias), but it got me thinking anyway. 

Is it because of a big pharma conspiracy? Is it because I'm in cahoots with the evil drug companies and all I want is money? Is it because I'm just too close-minded to be able to accept anything other than conventional medicines? Is it because I love seeing patients suffer? Well, in short no.

I find herbal medicines really interesting. Unlike homeopathy, which has no theoretical possibility of working, herbal medicines contain plant material with high enough levels of chemical constituents to cause a pharmacological effect. There's something quite beautiful about the concept of using plants for medicinal purposes. The problem with them lies in the fact that there just aren't enough studies done for us to be able to say whether they work, or more importantly, whether they harm. Whilst herbal remedies have enough "medicine" in them to make them work, this also means they have enough in them to cause adverse reactions, to interact with other herbs, medication, illnesses and so on. Without Big Pharma funding, though, its not that likely that large, well designed trials will be undertaken on them, so using herbal medicines can be a bit like shooting in the dark. Even if we don't find any documented issues with a herb, this doesn't mean none exist, it may just mean that nobody has looked at (or published) any issues yet.

St John's Wort is different. There is now a pretty large body of evidence to suggest that it works, and that it works better than placebo and as well as conventional antidepressants like the SSRIs. We also know a fair bit about its interactions and its adverse drug reactions... So that's great then, yes? That means healthcare professionals should all consider it as a better choice than the conventional medicines, with all their nasty side effects etc, right? 

Well, in my opinion: not always. Whilst we know a fair amount about it, the problem here lies with production, and the inherent variability in herbal medicines. Because they're made from plant materials, there can be a huge amount of variability in what each tablet contains.. Even if you're using a product licensed under the Traditional Herbal Registration scheme, there can still be variability between each batch, depending on where the plant was grown, the time of year/ day it was harvested, and what it was treated after it was harvested. So, if you get stabilised on one batch of medicine, the next batch may contain differing amounts of active ingredients, which could mean a whole host of things might happen: it might work better, it might start interacting with your other meds, it might trigger a side effect etc. Then, just when you're getting used to that batch, the next one is different too, etc etc.

I've come across a few enquiries where a patient wants to use St John's Wort as add-on therapy along with their antidepressants. It maybe doesn't occur to the patient or their GP/pharmacist etc that it actually works in a very similar way to a conventional antidepressant. Combinations of antidepressants are usually only done under specialist care (with a few exceptions) because combining them increases the risk of some very severe side effects such as serotonin syndrome- the same applies to St John's Wort. The fact it's "natural" seems to blindside people into forgetting the usual principles of how medicines work. 

This is before we even get into the territory of risks associated with self-treatment of what can be a very, very serious disease. Would I exclude use of St John's Wort entirely, for everyone? No, because it does appear to work. But do I treat it with as much (if not more) caution than I would an SSRI? Yes, because there's still not that much information about its safety in the grand scheme of things. So this sort of negates the point of it, to be honest.

Hopefully that explains a bit about why I'm cautious about herbal medicines.

Have a lovely New Year's Eve folks, see you again in 2013.

Hxxx