A proposed Merchants Quay facility was refused planning permission by Dublin City Council last July.
That decision has been appealed to An Bord Pleanála.
If approved, the supervised injection facility will run as an 18-month pilot scheme, seven days a week.
Councillor Tara Deacy says the facility is needed:
"The fact that we are now once again facing further delays in the facilitation of a safer injecting room in Dublin is appalling," she said.
"The benefits of providing supervised drug injection facilities include increased access to health and social services, safe hygienic drug use, reduced public drug use and associated nuisance.
"We are all aware that drug use in Dublin's public spaces is a matter of significant concern to the general public."
