A new report from the National Advisory Committee on Drugs and Alcohol shows that there were almost 19,000 opiate users in Ireland in 2014.
Opiate drugs include: Heroin Morphine, Oxycodone, Hydrocodone, Codeine and Fentanyl.
In addition to that figure, almost 13,500 of those users were in Dublin.
The majority of the users were male (69%) while around two-thirds of users were aged between 35 and 65.
Dublin's amount of opiate users are more than twice the amount of the national rate between the ages of 15 and 64.
NACDA have been able to keep the rate stable since 2011 but the prevalence in the older age bracket of 35-64 appears to be increasing.
"This may be due to an ageing cohort effect where existing opiate users are getting older while fewer younger people initiate into opiate use," NACDA said.
Chairperson of the NACDA, Professor Catherine Comiskey said the findings of the report "highlight the chronic nature of the opiate use problem."
"Estimates highlight the possible increases in the numbers of people using opiates within the 35 to 64 year age bracket.
"This is a phenomena seen across Europe and indeed across other chronic conditions as populations age. Again, it is essential that the new National Drug Strategy addresses this challenge and the possible comorbidities that arise as any population ages.
"It is important to remember that many seeking or currently in treatment are parents or grandparents and have additional health and social care needs."
Minister of State for Health Promotion and the National Drugs Strategy, Catherine Byrne, said that she "firmly believes in a health-led and person-centred approach to our drug problem."
She added: "Recently An Taoiseach launched our national policy Reducing Harm, Supporting Recovery, a health-led response to drug and alcohol use in Ireland which will guide us over the years to come."
You can read the full report here.