As part of a global warning, the United Nations has highlighted Hong Kong as one of the places where the abuse of appetite suppressants for slimming purposes is most prevalent. Substances that suppress the appetite, anorectics, require a doctor's prescription. Phentermine is the most common. A report released by the UN's International Narcotics Control Board in March ranked Hong Kong sixth in consumption of anorectics, after Brazil, Argentina, South Korea, the United States and Singapore. 'Anorectics, which are meant to be prescribed and monitored by doctors, also have a use in the treatment of life-threatening obesity or attention-deficit disorder. 'However, they are instead being used indiscriminately to feed the slimming obsession that affects some societies,' board president Philip Emafo said in the report. 'Effective intervention by local competent authorities is a must if this trend is to be reversed.' Hong Kong Medical Association council member Tse Hung-hing said the association had known for more than a decade that some doctors casually prescribe slimming drugs to patients. He acknowledged that the Medical Council's code of practice did not specifically state how doctors should prescribe particular slimming drugs, but said doctors could still be found guilty of professional misconduct if they prescribed dangerous slimming drugs to people who did not need to lose weight. 'I think the code of practice and the present guidelines are strong enough to regulate the profession, but the problem is that no patient makes a complaint against the doctors to the Medical Council,' he said. 'The council can only investigate a doctor after it has received a complaint from the patient or the victim.' Dr Tse said doctors should use their professional judgment to assess whether a patient should be prescribed slimming drugs.