The Queen's homeopathic pharmacist is selling ground-down fragments of the Berlin Wall to people who believe it will cure asthma and depression.
Ainsworths, which has held a Royal warrant since 1980 and also supplies the Prince of Wales, is charging up to £114 (NZ$216) for a large bottle of tablets leading to warnings that vulnerable patients are being exploited.
The "remedy" is made by grinding down pieces of the Cold War relic and diluting it multiple times with lactose, water and alcohol.
Edzard Ernst, emeritus professor of contemporary medicine at Exeter University, said producers believe the tablets convey a "spiritual force" capable of bringing people together.
Among the claims made online in favour of Berlin Wall are that it treats asthma, headaches, aggression, depression, and insomnia.
Ainsworth itself makes no claims on its website about the benefits, however last night the company refused to explain why it sells the products.
Professor Ernst, who criticises the homeopathic remedy in a new book, said belief in such products can be dangerous because they delay patients seeking conventional, evidence-based medicines.
"Homeopaths do not believe it is a pharmacological action, but it is a sort of vital force that is acting," he said.
"So the vital force, the spiritual force that was in the Berlin Wall, the intention that was in the Berlin Wall, is in the remedy."
He added: "It is not only bonkers but ineffective."
The Royal Family has long been sympathetic to alternative medicine and homeopathy in particular, medicines made from plant, chemical, mineral or animal sources, that are then highly diluted.
Ainsworths sells the Berlin Wall remedy on its website, costing £4.20 (NZ$8) for a 1g vial of lactose tablets, up to £120 (NZ$228) for 1,000ml in liquid potency (23% alcohol).
It holds a Royal Warrant from the Queen and the Prince of Wales, who is also patron of the Faculty of Homeopathy.
A spokesman for the firm accused Professor Ersnt of ignorance.