The report from Merchants Quay and Ana Liffey Drug Project comes as a rise in drug-related activity in Dublin city centre is expected to rise during the summer.
It finds that 14% of addicts say they take drugs in public areas.
The report “A Safer City for All” also points out that there is no crisis detoxification centre in the country.
The report found that of 125 addicts who tested positive for Hepatitis C only 18 were in treatment.
It said that there is a high-risk group of intravenous drug users showing a high incidence of unsafe injecting practices.