Consumers are urged not to buy or use two slimming products which contain undeclared hazardous ingredients.

The Department of Health made the appeal after a 13-year-old girl and a 26-year-old woman felt unwell after taking them.

The girl was sent to Princess Margaret Hospital for palpitations, insomnia, sweating and tremors on May 2. She was discharged two days later. Tests showed the slimming product she had taken - a green and white capsule bought online - contained sibutramine and phenolphthalein.

The woman came down with psychosis and hallucinations in mid-May. She went to Princess Margaret Hospital May 21 and was discharged today. The slimming product she had taken - red and orange capsules marked "Lasmi" - contained sibutramine and spironolactone.

Phenolphthalein is used for treating constipation but has been banned for its cancer-causing effect. Sibutramine is a western drug ingredient used as appetite suppressant. Its side effects include increased blood pressure and heart rate, psychosis and convulsions. People with heart problems should not take it.

Spironolactone is a drug used for reducing the amount of water in the body, to treat oedema and heart failure. It can cause headache, drowsiness and gastro-intestinal disturbances.

Products containing sibutramine or spironolactone must be registered before they can be sold in Hong Kong. They can only be sold on a doctor's prescription and dispensed under a pharmacist's supervision.