People who try or use drugs do so for the first time between the ages of 16 and 30, research has found.
The Onset and Lifetime Use of Drugs in New Zealand study, led by the University of Otago, was to determine the age when people first begin to use drugs for non-medical purposes.
The data for the research comes from an analysis of over 12,000 interviews of people aged over 16, carried out by the New Zealand Mental Health Survey (2003/2004), in conjunction with the World Health Organisation.
Half of the people surveyed had drank alcohol by the time they were 15, the study found.
Alcohol was the most commonly used drug, with 94% of people drinking it at some point in their lives.
Secondly came tobacco, with 51%, while cannabis was third at 41%. Much further down the scale were cocaine at 4.2% and heroin 2.9%.
The results were similar to those for Australia and the United States - except that cocaine use in the US was four times higher.
New Zealand, Australia and the US all had a high use of cannabis.
The study also looked at ethnic comparisons of drug use and looked at those born in New Zealand under the age of 45.
It found that Pacific people had a delayed onset of alcohol use, and were less likely than Maori and other ethnic groups to ever use drugs.
Strategies to combat drug use and abuse should start in adolescence, not only through schools, but also through interventions at local and national levels, the researchers said.