The Duchy Originals brand was established by the prince in 1990
Advertisements for two herbal medicines from Prince Charles's Duchy Originals company were misleading, a regulatory authority has ruled.
The firm has been told to change the wording of the website adverts after a complaint about claims concerning the effectiveness of the remedies.
The Medicines and Healthcare products Regulatory Agency (MHRA) stepped in and upheld the complaint.
Earlier this month, a Duchy detox product was criticised by experts.
Adverts for Duchy Herbals Echina-Relief Tincture and Duchy Herbals Hyperi-Lift Tincture appeared on the company's website in January.
A member of the public alleged the campaign suggested the two products had been assessed for efficacy and was therefore misleading.
The MHRA gave Duchy Originals a licence to sell the remedies but did not enable it to make any claims about the effects of the remedies.
A MHRA spokesman said: "Nelsons, the registration holder, on behalf of Duchy Originals agreed they would amend their advertising and remove claims of efficacy from their website and all future advertising."
The Duchy Originals brand was established by the Prince in 1990 "to promote organic food and farming and to help protect and sustain the countryside and wildlife".
Earlier this month, a leading scientist accused Prince Charles of exploiting the public in times of hardship by launching what he called a "dodgy" detox mix.
Edzard Ernst, the UK's first professor of complementary medicine, said the Duchy Originals detox tincture was based on "outright quackery".