The number of heroin addicts receiving treatment in the Eastern region grew by over 15 per cent last year, according to a report from the Eastern Regional Health Authority.
The report said there were now 5,844 people in the region receiving methadone treatment, an increase of 15.5 per cent since January 2001.
The fact that growing numbers are being treated may be as a result of an increase in the number of treatment places in the region. An additional 784 places were created during 2001.
The figure for those now availing of treatment includes approximately 200 heroin addicts in prison.
The ERHA's annual report also said heroin use remains "almost exclusively a Dublin phenomenon", with approximately 13,500 users in the city. It put the number of people using heroin in the State at up to 15,000.
"While cannabis, followed by ecstasy, is the most common drug of use in Ireland, it is heroin that has the greatest impact in terms of harm to the individual, family and community," the report said.
"Studies of trends in drug use also indicate a steady increase in the use of cocaine, particularly among young professionals".
It said the average drug-user was male, less than 30 years old, generally with a poor education and unemployed.
"The age profile of drug misusers in treatment is declining," it noted.
"Disadvantaged populations such as the Traveller community, homeless persons and persons working in prostitution are acknowledged to be at increased risk in terms of increased drug misuse," it added.