The European Commission is promising tighter rules on 'legal highs' despite surveys indicating that most people think such action should be based on medical evidence.

Synthetic drugs - the most infamous was labelled meow-meow by the tabloids - mimic the effects of illegal substances like ecstasy and speed. Sold online or through "head shops" as bath salts or plant food they can be entirely synthetic versions of existing drugs or plant-based products, often cathinone, extracted from khat.

The EC said it found 41 new substances available, compared to 24 last year: so the ban is working well. Since 2005 Brussels has recorded 115 substances. In 2009, 24 were logged and in 2008 another 13.

The Commission currently runs an early-warning system for new substances. It said this was working well but was in danger of being overrun by the number of new products hitting the market.

Eurocrats will consider changes to criminal law, new types of monitoring and aligning drug control with food and drink safety measures. It will report back with options to consider in the autumn.

But designer drug-makers, often churning out product from labs based in China, tweak existing drugs in response to slow-moving legislators. For example, labs have moved away from mephedrone since it was banned.

The moves mean that medical staff who are dealing with patients who have taken designer drugs have little or no information on what the likely long or short-term impact of the substance may be. And it leaves drug users with a steep learning curve as they move onto new substances.

Commission research found use of "traditional" drugs was generally stable. Dealers are keener to sell the "legal" highs because they can make just as much cash with no risk of prison.

The rule change coincides with a European-wide survey into attitudes to drugs which found that 5 per cent of teenagers had tried synthetic drugs. In Ireland this rose to 16 per cent against 8 per cent in the UK.

It found just 26.3 per cent of UK teens supported banning such substances without evidence. Altogether 58.3 per cent of UK teens said they should be banned if they were found to damage health.

Tabloid outrage about mephedrone or meow-meow led then Home Secretary Alan Johnson to ban the substance in March 2010.

The Commission noted that 8,500 EC citizens die each year from drug overdoses.

Some details on the new policy for synthetic drugs is here, and the survey results can be downloaded here