The number of different legal highs readily available in shops and online has rocketed in the last year and the European Union drugs agency has warned there will soon be too many to control.
The European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), in association with law enforcement agency Europol, said that new legal highs are appearing at an "unprecedented pace". They discovered 41 new types of psychoactive substances in 2010, compared to 24 found in 2009 and 13 in 2008.
Fifteen of the 41 new substances are synthetic cathinone derivatives, which imitate the effects of ecstasy, cocaine and amphetamines. This group includes the drug mephedrone, also known as MCAT. This type of drug was banned in Britain last December.
About a quarter of the legal highs identified in 2010 were synthetic cannabis drugs. One such drug is Spice, which is often marketed as potpourri, and was banned and made a class B drug in Britain in 2009.
But the drugs agency also discovered new derivatives of known drugs PCP and ketamine. These drugs are being created in illegal laboratories in south-east Asia and are finding their way into the UK through specialist shops and the internet.
Since the drugs are marketed as legal highs or plant food and purport to not be intended for human consumption, they can sidestep drug laws and are able to be sold online or in 'smart' shops and 'head' shops.
And with new substances being produced at an alarming rate, the EMCDDA is concerned by its lack of "ability to anticipate emerging threats".