Almost 10,000 people approached Merchant's Quay Ireland for help with addiction, mental health and homelessness last year.
The charity's annual report reveals that more than 2,500 individuals used its needle exchange service, with 421 of these presenting for the first time.
It is calling on the Government to provide proper supports for homeless addicts while they are in emergency accommodation, like mental health counselling and detox programmes.
CEO Tony Geoghegan says a lot of the focus is understandably on homeless families but that means others are left behind.
He said: "The effect of that is that single people, and particularly single people with drug, alcohol and mental health issues get filtered right down to the bottom.
"Then there are other people unfortunately who end up, and we know that we currently have about 150 people sleeping on the streets, but wheras in our own night café we have up to 70 people there that would otherwise be sleeping on the streets."