Drugs, sold as "new" or "strong heroin", that led to overdoses in Cork and Dublin, have turned out not to contain heroin at all.
Chemical testing has found the substances were made up of potent synthetic opioids called nitazines, that were mixed with paracetamol and caffeine.
The drug was found to be 25 times stronger than fentanyl, and available in pill or powder form.
17 people in Cork and 57 people in Dublin overdosed after taking the drug late last year.
Professor Eamon Keenan is National Clinical Lead for Addiction Services in the HSE
"When the problem first arose here in November we were told that people were selling what was called "strong" heroin or "new" heroin but when we ended up doing the analysis we identified that that there was no heroin in the product and it contain the nitazine drugs at low levels but obviously high enough levels to cause overdoses and problems"
