Anyone up for joining me outside Boots at 10:23 am for a homeopathic overdose?

This Saturday, 30th January - by which time I seriously hope I will have sent off my tax return - if all goes well, you will find a gawky fair-haired woman with glasses and big teeth overdosing on homeopathic medicine outside the Boots in Haverfordwest, Pembrokeshire.

Now, why am I doing such a damn silly thing?

Well, nationwide - and, even, internationally - a few hundred other people are doing exactly the same thing for the Ten 23 campaign. Their slogan is: "Homeopathy: There's nothing in it."

You can read more on the above link about homeopathy - and I'm sure many homeopaths will be glad to tell you their side of the story. Shelley the Republican also promises miracles from it . . . (sorry, couldn't resist!). Anyway, the basic principle is that a tiny amount of something that causes the symptoms someone is suffering from should be taken, and the more dilute, the stronger it is. When atoms and molecules were discovered, and simple arithmetic points out that it is unlikely that a single molecule of the active ingredient will remain, the homeopaths suggested that "water has a memory". In other words, the water should "remember the ingredient".

As Ben Goldacre points out in his book, water molecules are tiny, and this is rather like expecting several bags of peas to "remember" the shape of a sofa. And as Crispian Jago puts it, let's hope they don't remember all the other things they've surrounded - bearing in mind that water molecules are mostly millions or billions of years old . . . Homeopaths get around the latter point by claiming that beating a vial of said water 10 times against a horsehair something-or-other will "make it forget" everything else. As for the former? Ummmm . . . I think just by getting extremely angry.

At this point several people will say, "But homeopathy worked for me." What is more likely to have happened is that you got better because you were going to get better anyway - this is called "regression to the mean". Also, the act of taking something gave you a feeling that something changed, and lifted your expectations. This encouragement, and feeling of being looked after itself, might boost your feeling of general well-being. This is called "the placebo effect", and study after study finds that homeopathy works no better than this. You can read more about the placebo effect here.

In the meantime, how do they turn this magic water into pills? Well, it appears that they drip it onto sugar and then let it evaporate. I hate to break it to you, but, yes - the water is no longer there. And molecules of sugar fit in between water molecules, not around them so as to take up some weird shape . . .

I can well imagine that a carer or doctor and their patient might well benefit everyone by giving people who are permanently stressed a placebo - their real problem is they are over-tired, not looked after, depressed, or just a general whinger. But this comes at a cost. It avoids dealing with the person's real problem - and it boosts sham science and medicine.

Which brings me to why the Ten 23 Campaign are picking on Boots especially. Boots is a trusted high street chain, supposed to be very knowledgeable of medicine, and to provide customers with the best treatment. Therefore, the campaign is asking them not to sell pseudoscience because it is not in the customer's best interest. As we point out, it is really not the best option, and can indeed be dangerous if real treatment for a real problem is delayed or rejected.

Boots themselves admit that this is pseudomedicine, but they continue to sell it "for consumer choice". That is a classic example of assuming market forces make the best choices. They don't. Everyone wants to sell their product, and will mislead people into thinking that it will do more than it really will. Market forces are routinely manipulated, and Boots is merely taking advantage of this to make more money.

Oh, and for anyone who's reading this and concluding that I'm in the pay of "Big Pharma" - well, for one thing this is not America, and we get all our prescription medicines free in Wales, so I can't see that that makes them a big profit. More seriously, yes, the pharmaceutical industry has plenty of faults (I could go on and on about what some certain people do to doctors trying to publish research they don't like . . . !). But this does not somehow magically make alternative medicine work. Conventional and alternative medicine are not opposites, or black and white in some way. The difference is that conventional medicine passes the scientific tests, and alternative medicine does not.

Returning to the question of "consumer choice": a real choice is an informed choice. To make a guess at what to buy, on the basis of a random person's statement that "Big Pharma is evil" or "homeopathy worked for me, I don't pretend to understand the science but it works" is not much of a choice - and many people do not have the education or the information at hand to sift through the truckloads of different advice. This morning I went to the Boots in Haverfordwest to check out their homeopathic range.

I found it under a big sign that said "Alternative Medicines". Vitamins, herbal remedies, and weird packet soups seemed to appear on the shelves at random amongst the homeopathy. There were an awful lot of 3 for 2 offers, and very little on-shelf labelling, so I had to pick up individual products to see what was homeopathy and what wasn't. There were dozens and dozens of bizarrely-named little vials, such as "Sulphur" and "Nux Vomita" (lovely!) - and no information at all about what symptoms they were supposed to treat. I finally bought the one product that actually did indicate that, namely "Nelsons Arnica 30c pillules".

There is a little logo of a green leaf with a white cross, disturbingly - and obviously deliberately - similar to the green cross on a white background of pharmacies. It describes itself as "Arnica Montana: A homeopathic medicinal product used within the homeopathic tradition for the symptomatic relief of sprains, muscular aches and bruising or swelling after contusions."

It also contains several warnings. I must not overdose (oh dear!). I must consult a doctor if I do that, and bring the medicine with me. I must also consult a doctor if I use while pregnant or breastfeeding. When taking the medicine I must take extreme care not to touch it with my hands, but must empty the pills into the cap and then into my mouth. If symptoms persist or worsen after 7 days I must consult a doctor. And I must not use after the expiry date has passed.

To be fair on Boots, or more likely the law generally, I think there was a tiny label on the shelf noting that it was "without approved therapeutic something or other" (sorry about that; I thought it was on the product but I now can't find it - I will go back and check on Saturday). But everything else about it suggested that this was a proper medicine.

I took it to the counter and handed it to the nice lady on the other side, and asked innocently, "I was wondering, how do these things actually work?" She opened it up to show me how to open the product, and explained that it was to treat bruises and sprains, so I made a minor remark about getting bruises all the time (which is true - I'm always walking into things). She also advised me to take it before an operation because it would reduce the bleeding. I asked vaguely, "It's this like cures like business, isn't it?" She looked perplexed, but said "Yes". I couldn't go on. I'm a terrible liar. I just bought it and managed to get out of the shop before I doubled up with laughter.

When I got home, my mum read the packaging even more carefully with me, and laughed even harder. She then raced to look up arnica. She knew, of course, that it's a traditional medicine in folklore, rubbed on the skin where there is bruising, and it does seem to have some useful properties. She found out how it works: it encourages vasodilation, the slight enlarging of blood vessels to let more blood through. This is what happens on your skin when, for example, you feel hot or you blush. So it is logical that this would deal with the bruising faster: the blood would take away the waste products and disintegrating blood cells, and bring along the materials to mend it.

The main principle of this, of course, is that this is a product to be rubbed on the skin. Not to swallow. If you swallow arnica in a large enough quantity, why, presumably you get the vasodilation inside your digestive system. In any case, you certainly get severe gastroenteritis and internal bleeding. Now, if I had reason to believe that there was sufficient arnica in this complex glass vial I've spent £5.19 on, I'd be doing something very dangerous indeed.

It doesn't even follow homeopathy's own dogma of "like cures like". If a tiny trace of ingredient which causes the symptoms is supposed to treat them - as I think is supposed to be their philosophy - shouldn't it follow that this medicine is supposed to treat gastroentiritis and internal bleeding? Or, perhaps, that it should cause more bruising on the skin rather than less? Well, I'll let you know after Saturday morning!

I want to thank @irlbinky on Twitter for his huge encouragement and support, and my other fellow skeptics @Zeno001, @JackofKent, @Crispian_Jago and many others. And also hoping to see another fellow Twitterer there on Saturday, if it turns out he can make it (as I don't think he's visited this blog yet he might not want me to give his name.) And I hope to tell you a lot more this coming weekend.