It is estimated Europeans are spending around €30bn a year on illegal drugs.
A new EU Drug Markets Report found cannabis to be the most popular substance followed by cocaine, heroin and then amphetamines.
The research also found some 25m Europeans aged between 15 and 64 have tried cannabis in the past year.
While opioid use such as heroin accounts for the largest proportion of harm including death.
The same research revealed that cannabis is the main drug for up to 80% of young people being treated for mental health issues, according to a child psychiatrist.
The research shows a clear link between use of the substance and a reduced brain structure in teenagers.
The finding is part of a decade long study of 2,000 European teens, and it suggests one or two joints is enough to damage an adolescent's brain.
Meanwhile, earlier this evening, Revenue confirmed they seized 13.5kgs of cannabis resin worth over €80,000 in Dublin today, just 24 hours after €20,000 was seized in a separate operation.