Up to 1,000 people in Northern Ireland are problem heroin users, according to a new report.
The report found that the number of problem users in the 15-29 age group was approximately double the rate among people aged between 30 and 54.
The survey also revealed that over half of those involved did not receive any treatment for their addiction during the 12-month period of study from November 2000 to October 2001.
Heroin users in Ballymena, County Antrim, were more likely to be male, younger, and injecting more than in other areas, while users in Belfast were more likely to smoke than inject.
The study is the first of its kind which looks into the scale of heroin usage.
Northern Ireland Drug and Alcohol Co-Ordinator, Jo Daykin, said it provided a reliable baseline of the number of problem heroin users.
Ms Daykin said it will now be easier to plan and target services more effectively.
Problem users are described as individuals who had experienced significant social, psychological, physical or legal problems associated with dependence, intoxication or regular consumption of heroin.
The study was commissioned by the Drug and Alcohol Unit of the Department of Health and was carried out by Dr Karen McElrath of Queen's University in Belfast.
