The "sophisticated" marketing of ecstasy is behind a rapid rise in its use by young Europeans, a report has found.
Tactics such as branding, shapes, colours and even the use of superhero logos have coincided with an explosion in its use, the 2016 European Drug Report said.
The UK reported the second highest level of use of the drug in Europe, with 3.5% of young adults admitting using it in the past year, behind the Netherlands’ 5.5%.
And ecstasy, also known as MDMA, is now much stronger than ever before, thanks to the better availability of chemicals.
The use of ecstasy had been falling since a peak in the mid-2000s, but at least 2.1 million people aged 15 to 34-years-old used the drug in the past year, the Europe-wide report said.
This is an increase of some 300,000 on 2015.
The drug's comeback can be in part explained by a previous shortage of essential chemicals needed to produce ecstasy in a potent enough quantity.
As the shortage has come to an end, stronger forms of ecstasy have come to market.
The UK reported the second highest level of use of the drug, at 3.5% of young adults admitting using it in the past year, behind the Netherlands’ 5.5%.
The drug is no longer “sub-cultural” or niche, and is taken by a greater number of younger people at bars, private parties, music concerts and festivals.
Traces of ecstasy in drainwater were found to be higher in 2015 than in 2011.
There had been "deliberate strategies" by distributors to enhance the reputation of the drug.
New efforts to reduce harm from the drug will need to counter the innovation in marketing and online retailers, the report added.
Greater Manchester Police reissued a warning about ecstasy after a teenager overdosed on a 'Rockstar' version of the drug this month.
The force issued several warnings about the dangers of taking the party drug after one teenage girl died and two women were taken to hospital after all taking variations of ecstasy.
It follows the discovery of pills shaped like Lego bricks.
Alexis Goosdeel, the EU drugs agency director, said: “The revival of MDMA brings with it the need to rethink existing prevention and harm-reduction responses to target and support a new population of users who may be using high-dose products, without fully understanding the risks involved. Intoxications and even deaths associated with this drug are highlighted in our new report."