More than 7,600 people received opioid-substitution treatment in the first six months of this year.
In the vast majority of cases, this is used to treat heroin-addiction.
In Ireland, the main treatment for opioid addiction involves methadone and the drug buprenorphine.
According to details released under the Freedom of Information Act, 7,645 people received opioid-substitution prescriptions from a community pharmacy in the first six months of this year.
This included 5,200 men and 2,400 women.
Nearly 4,500 were prescribed by doctors in Dublin, while there were also high numbers in Cork, Limerick and Louth.
Dr Austin O'Carroll, a GP in Dublin's inner city, said Ireland has a huge problem with heroin addiction.
“I would be seeing up to twenty people who have addiction problems every day,” he said.
“I would see two to three new people a week who are seeking heroin treatment.
“I would also see significant addiction to other drugs – particularly benzodiazepines. I would have people coming into me, many of them on up to 30 or 40 tablets a day.
“Also crack cocaine is an increasing problem in the inner city as well.”
According to the figures, some 8,357 people received opioid-substitution prescriptions last year – a 4% increase on the 8,059 who received them the year before.
Dr O’Carroll said many more heroin addicts are not accounted for in the figures.
“I know from my own work that there are still people who are not on treatment – a number who need treatment” he said.
“My own belief is that heroin addiction and addiction in general is very much a product of depravation and inequality. Ever since the recession in 2007, in my own work I have seen this increasing significantly.”
Many people would also be treated in a clinic, such as the National Drug Treatment Centre in Pearse Street in Dublin.
It had a 26% per cent increase in the number treated for heroin addiction last year, with 398 patients seen in 2019.
Some 230 people have been treated at the centre so far this year.
Reporting from Eoghan Murphy