Use of new synthetic drug in the UK dropped after it was outlawed, but users continue to search for “legal highs,” disregarding lack of scientific research, according to a study.

Mephedrone use in the UK exploded in 2008 before the drug was made illegal in 2010. Since then, the street price has risen and the quality degraded, causing users to look elsewhere for their fix.

"Drug users today are attracted to new substances that are pure and have few adverse effects,” said lead researcher Tom Freeman of University College London. “Lack of scientific research on the effects and risks of new legal highs might explain why young people rely on subjective reports from friends or the Internet when deciding whether to try a new substance.”

According to the study, in 2010, 41 new substances were detected in the EU, compared with 24 in 2009 and 13 in 2008. Of those 41 new substances, 15 are synthetic stimulants, just like mephedrone.

The study is published online in the journal Addiction.