Hundreds of people are planning to "overdose" on homeopathic remedies outside Boots stores to protest against the chemist selling treatments which critics say are ineffective.
The protesters will drink large quantities of homeopathic fluids to illustrate their claim that the potions are too diluted to have any impact on the body.
Homeopathy has grown from an obscure alternative remedy to become a multi-million pound industry in the UK, with Prince Charles among its high-profile advocates. But critics say there is little scientific backing for its claims to ease conditions including asthma, migraine, irritable bowel syndrome, arthritis and depression.
Campaigners have already lobbied for the NHS to reduce its £4 million annual spend on homeopathic remedies and are now targeting Boots for profiting from what they claim is an "unscientific and absurd pseudoscience".
The Boots protests planned for later this month have been organised by campaign called 10.23, which grew out of the Merseyside Skeptics Society, a group of rationalist thinkers.
They will take place on high streets in Edinburgh, Manchester, Bristol, Liverpool, Glasgow, Birmingham, Southampton and London, with sympathy protests in Australia, Canada and the United States.