The 'legal highs' that leave users feeling low

China's teenagers face a growing threat from a new class of drugs called New Pyschoactive Substances that are easy to manufacture and obtain. Zhang Yi reports.

Zhang Ling (not his real name) will never forget the evening he walked into a club and consumed what he thought was a regular soft drink.

Eight years later, he is still suffering the consequences of the instant euphoria brought on by the 50 yuan ($7.70) drink, which contained a powerful "legal high". He now lives in a voluntary drug rehabilitation center in Beijing, attempting to overcome an addiction triggered by the bottle of "Cough Syrup", a preparation that contained large amounts of codeine.