Preliminary figures on drug-related deaths show there were over 400 fatal overdoses in 2020.
The findings by the Health Research Board (HRB) are being presented at the Citizens' Assembly on Drugs Use today.
The third meeting of the assembly is focusing on the role of the health and community sectors in significantly reducing the harmful impacts of illicit drug use.
According to the HRB, 409 deaths in 2020 were poisonings and eight in ten of those deaths involved more than one drug.
The research shows that seven in ten deaths involved opioids.
Methadone was implicated in three in ten poisoning deaths and heroin was implicated in two in ten.
Benzodiazepines related to six in ten deaths while three in ten involved cocaine.
Almost six in ten deaths involved other prescription drugs, most commonly antidepressants and antiepileptics.
Dr Suzi Lyons who is a Senior Researcher at the Health Research Board said the findings showed that mixing drugs was a major factor in poisoning deaths.
Dr Lyons said: "We also see that the growing prevalence of cocaine use in society is reflected in deaths with cocaine implicated in 130 deaths in 2020 compared to 24 in 2011."
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The research also looked at the stark socio-demographic characteristics of people who died from poisoning.
More than six in ten were male and more than half of the men were aged 42 or younger.
More than half of the women were aged 45 or younger.
Half of those who died from poisoning had mental health issues, one in eight were homeless and one in five had never injected.
In four out of ten of the deaths, the person was alone, while 11% died in homeless accommodation.
Around 9% died in a public place or building.
The findings by HRB note that there were 397 non-poisoning deaths among people with a history of drug use.
Chief Executive Dr Mairéad O'Driscoll said the findings clearly demonstrated the impact that drug use has in Irish society and could help to inform preventative measures to save lives.
The Chairperson of the Citizens' Assembly described figures from the Health Research Board as grim and stark.
Paul Reid described the latest figures as a wake up call for legislators and the public.
The third meeting of the assembly follows the initial focus on national policy and understanding the harmful impact of illicit drug use.
The 99 members led by Independent Chairperson Paul Reid will consider health-led and community-based measures that could potentially form part of the Assembly’s final recommendations later this year.
This weekend, there will be contributions from experts in health-led strategies from Portugal and Austria; which are countries regarded as "leading the way" in reducing the harmful impact of illicit drug use.
In autumn, the meetings will consider criminal justice issues, current and proposed legislation, prevention measures, and public awareness.
