Side effects: The Health Department says the slimming pills contain ingredients which may increase blood pressure and heart beat.

The Health Department urges people not to buy or use the slimming product Chao Nongsu Qingzhi Jiaonang as it contains Western drug ingredients and may cause side effects in heart-disease patients.

People who have been using the product are advised to stop taking it immediately and to see a doctor if feeling unwell.

The product, packaged under the name of OPC Care, was not registered under the Pharmacy & Poisons Ordinance.

The department obtained a product sample from a woman after receiving an enquiry earlier this year about its safety.

The woman brought the product from the Mainland and it was found to contain sibutramine and mazindol.

Under the ordinance, products containing these two substances must be registered before sale and can only be sold on a doctor's prescription and under a pharmacist's supervision.

Sibutramine can cause increased blood pressure and heart rate while Mazindol can lead to nervousness, irregular heart beat, insomnia, dizziness, headache and stomach cramps.

Anyone with the product should dispose of it or submit it to the Public Health Laboratory Centre, 382 Nam Cheong Street, Kowloon.