The warning comes after Thurrock Council’s trading standards officers caught an importer at Tilbury Port importing unsafe products.
Officers seized the skin lightning creams containing the banned substance, which can cause cancer, liver damage and other illness.
Hydroquinone is a bleaching agent, which is often used in skin lightening products. Since 2001, it has been illegal for the substance to be available in cosmetic products that are sold over the counter.
When buying skin creams, members of the public are advised they should check the label to ensure it does not contain hydroquinone.
If they see any trader selling unsafe cosmetics or are unsure if the product they are using is safe, then they can call Consumer Direct in confidence on 0345 040 506.
Cllr Phil Smith, the council’s portfolio holder for public protection, said: “It’s very pleasing to note that our trading standards team has found this illegal product, it’s just sad people are trying to sell it.
“I find the selling of dangerous and illegal products to unsuspecting people abhorrent and only hope the team will continue to stop other dangerous products before they reach our residents.
“There can be no excuse in this instance – the chemical has been banned for 12 years! This is unscrupulous and irresponsible behaviour, they are putting money before public health.”
He added: “I would strongly urge the public to get in touch with Consumer Direct if they have bought any products containing hydroquinone.”