Some Han's Skin Care cosmetic products have been found to contain potentially harmful, undeclared ingredients, said the Health Sciences Authority (HSA) in a press release on Friday.

The HSA is advising members of the public to stop using and discard the affected products: the brand's Flawless Day Cream, Flawless Night Cream, Treatment Toner, Trial Flawless Day Cream, Trial Flawless Night Cream, and Trial Treatment Toner.

People who have used these products should seek medical help if they have experienced adverse effects or are concerned about their health, said the HSA. The authority also stressed the dangers of purchasing health products, including cosmetics, over the Internet.

"Consumers need to be aware of the risk of purchasing products online. Consumers should exercise discretion in their purchase of cosmetic products, and purchase them from reliable and reputable sources. Unlike other commodities, use of poor quality and falsely labelled health products including cosmetics can cause serious health effects," said Associate Prof Chan Cheng Leng, deputy group director of the Health Products Regulation Group at HSA.

The HSA was alerted to these products after receiving feedback from concerned consumers questioning the safety of Han's Skin Care products sold online.

These were found to contain ingredients like hydroquinone and tretinoin, which are used in Western prescription medicines to treat skin conditions. These ingredients are prohibited in skincare cosmetic products and should be used only under medical supervision because they may cause harm if used incorrectly, said the HSA. Hydroquinone can cause reactions and changes in skin colour, while tretinoin could lead to redness and peeling of the skin.

The products were also found to contain mercury - also prohibited in cosmetic products because it can lead to rashes, skin discolouration and blotching - and salicylic acid, which can cause dry, irritated and red skin.

HSA investigations are still ongoing.

It is an offence to import, sell and supply an illegal or unapproved health product. Anyone found guilty of an offence under the Health Products Act can be fined up to $100,000 and/or jailed for up to three years.

Members of the public with information that could help with investigations can contact the HSA at 68663474 or e-mail it at hsa-is@hsa.gov.sg. They can also report any other suspicious sales of illegal products to the HSA.