Boots said homeopathy was recognised by the NHS
Homeopathy sceptics have staged a mass "overdose" of homeopathic remedies, in a bid to prove they have no effect.
Protesters ate whole bottles of tablets at branches of Boots in places such as Liverpool, Manchester, Glasgow, London, Leicester, Edinburgh and Birmingham.
They have asked the pharmacy chain to stop selling the remedies, which they call "scientifically absurd".
The Society of Homeopaths called it a "stunt". Boots said it followed industry guidelines on homeopathy.
From 2005 to 2008 the NHS spent almost £12m on homeopathic treatments, according to a 2009 Freedom Of Information request by Channel 4 News.
Supporters of homeopathy say it is a system that uses very highly diluted substances to trigger the body to heal itself, but critics argue there is no evidence they work.
HAVE YOUR SAY
I believe herbal remedies can help various ailments but I'm very sceptical about the preparations that are sold
The demonstrations were organised by the Merseyside Skeptics Society (MSS).
Michael Marshall, from the MSS, said: "We believe that they shouldn't be selling sugar pills to people who are sick. Homeopathy never works any better than a placebo. The remedies are diluted so much that there is nothing in them."
Mr Marshall said demonstrations were also planned in Canada, Spain, the US and Australia.
The Society of Homeopaths said it did not expect the protesters to suffer any adverse reactions from taking large quantities of the remedies.
The society's chief executive, Paula Ross, said: "This is an ill advised publicity stunt in very poor taste, which does nothing to advance the scientific debate about how homeopathy actually works."
Paul Bennett, professional standards director from Boots, said the company follows advice from the Royal Pharmaceutical Society of Great Britain on the correct selling of complementary medicines.
He said: "Homeopathy is recognised by the NHS and many health professionals and our customers choose to use homeopathy.
"Boots UK is committed to providing our customers with a wide range of healthcare products to suit their individual needs, we know that many people believe in the benefits of complementary medicines and we aim to offer the products we know our customers want.
"We would support the call for scientific research and evidence gathering on the efficacy of homeopathic medicines. This would help our patients and customers make informed choices about using homeopathic medicines."