More than 12 people a week die from overdoses or drug-related causes in Ireland, a new report shows.
Latest figures reveal a slight drop in the number of drug deaths, down to 633 in 2012 compared with 645 the previous year.
Analysis by the Health Research Board (HRB) shows one in three of those who died had a history of mental illness.
Alcohol and benzodiazepines – including tranquilisers like diazepam – play a big part in the number of deaths through drug poisoning, each being involved in a third of all overdose deaths, the study shows.
Graham Love, chief executive at the HRB, said mixing drugs was increasingly proving to be lethal.
“What is clear is that alcohol remains the substance implicated in most poisonings, polydrug use features in more than half of poisonings and we continue to see an increase in the number of people dying by hanging,” he said.
But he added the figures also reveal that interventions can reduce deaths.
“Since 2004 there is a sustained decrease in the number of deaths among drug users linked to road traffic collisions, which have fallen by 62% since 2006,” he said.
“This correlates with tough drink-driving campaigns from the Road Safety Authority and the introduction of random breath testing in 2006.
“We would hope that the new roadside impairment testing, and measures in the upcoming Public Health Alcohol Bill, will result in a further decline in drug-related deaths in the future.”
Some 350 people died as a result of poisoning, or overdose, while 283 were drug-related including suicide, drowning or death by medical causes, such as liver failure.
Half of all poisoning deaths were people under the age of 40 – with three out of four men.
Methadone was involved in a quarter of the poisoning deaths, in most cases mixed with another drug.
More than half of the victims died after taking a mixture of drugs, a massive jump of 60% in polydrug deaths since 2004.
The study also shows a drop in heroin deaths, down to 61 from a peak of 115 in 2009.
Of the non-poisoning drug deaths, half of those who died were under 29 years of age.
Eight in 10 were men and more than half had a history of mental illness.
Some 5,289 people have died from overdoses and drug-related causes since records began in 2004.