Martin Robbins: Magic potions must not be sold next to real medicines

Homoeopathy is a bizarre relic of the 18th century, a magical ritual cast over water or sugar pills, claiming to create medicines but failing to pass objective testing. In spite of this, a £40m homoeopathic industry prospers in Britain. You can buy homoeopathic vaccines, or go on a homoeopathic diet. Homoeopathic explorers travel to African clinics, claiming to be able to treat Aids. One site even advertises homoeopathic urine for your children, which is taking the, er, mickey.

Believers claim something that causes symptoms can cure them, as long as it's diluted so there's none of the original substance left. So caffeine could cure insomnia, if diluted to the extent that all you have left is water – the remedies contain no active ingredient. Supposedly the water keeps a "memory" of the caffeine that was in it. The memory is only activated when tapped in a certain way, allowing it to remember the active ingredient while conveniently forgetting the sheep that died upstream of the water supply.

These curious beliefs violate the laws of physics, and homoeopathy has never been convincingly shown to be effective. Some people do feel better after taking a homoeopathic remedy, but this is easily explained by the placebo effect, and the fact that most sick people get better anyway.

You might argue it's harmless, but at a time when public services are facing cutbacks, taxpayers are forking out over £4m per year for it on the NHS. Public health may be at risk too. Selling homoeopathic products alongside medicines may fool people into believing they are equivalent. People may delay or avoid treatment, believing they are managing their condition with homoeopathy, and advice from homoeopaths can, in some cases, be dangerous – in 2006 a Newsnight investigation found homoeopaths advising people to take "alternative" anti-malarials.

Responsible pharmacists should not be selling magic potions alongside real medicine, and the Government should not be wasting millions encouraging this. It is shocking that we are paying for a medicine that appears to have nothing in it.

Martin Robbins is a scientist and writer who blogs at layscience.net