The Health Sciences Authority (HSA) has advised people not to buy or use a health product labelled "TCM Recipe Licozen Ointment".
The product has been tested and found to contain very high levels of arsenic, the HSA said in a press statement yesterday.
It added that sellers should stop the sale and distribution of the ointment immediately.
The authority was alerted to the product by a doctor, after a woman said there was dramatic improvement in her young child's chronic eczema condition shortly after applying the ointment. She had bought it from a store in the central part of Singapore, the HSA said.
The product was also advertised on various online platforms, supported by numerous testimonials claiming, among other things, that it was a "superior alternative to cure skin disorders" when other medical treatments fail, the HSA said.
It added that the mother of the patient was advised to stop using the product immediately after laboratory tests showed that it contained very high levels of arsenic.
Arsenic is a toxic heavy metal and it can cause skin irritation, contact dermatitis (with symptoms such as skin rashes and blisters) or rashes resulting in skin peeling when applied externally, the HSA said.
Widespread, prolonged application and accidental ingestion of products containing high levels of arsenic can increase the chances of arsenic poisoning.
Possible symptoms of arsenic poisoning include vomiting, abdominal pain and breathing difficulties. The risk of experiencing these harmful effects may be higher when used by young children or on broken, inflamed skin, the HSA said.
Dr Mark Koh, head and consultant, dermatology service at KK Women's and Children's Hospital, said that while arsenic helps to relieve inflammation, high quantities of it are toxic.
None of the Western medications for eczema contains arsenic, he said, but it can be found in some traditional Chinese medicine.
He cautioned against buying medications online or from unknown overseas sources as they may not come with detailed instructions on how they should be used.
The HSA advised people who bought or are using the product to stop using it immediately. Those experiencing any adverse effect or are concerned after using it should see a doctor as soon as possible.
"Be wary of any health product promising miraculous results or which makes exaggerated claims such as 'no side effects' and '100% safe'," the HSA said, adding that people should also be wary of products that promise unexpectedly quick recovery from chronic medical conditions .
Sellers who do not stop the sale and distribution of the product immediately face a fine of up to $5,000 and up to two years' jail under the Medicines Act if convicted.
People who have any information on the sale and supply of the ointment or other illegal products can contact the HSA's Enforcement Branch on 6866-3485 during office hours on weekdays.