The HSE has sent out a warning as receiving over 40 drug overdoses have been reported in the space of 36 hours.
There have now been 42 overdoses - up from a reported 24 this morning.
Traces of a nitazene-type substance has been detected in heroin samples linked to a cluster of overdoses recorded in the Dublin area.
Forensics Science Ireland are continuing to analyse more samples.
Nitazenes are strong synthetic opioids and are deemed as having a substantial risk due to their high potency.
Professor Eamon Keenan, HSE National Clinical Lead, Addiction Services, urged "extreme caution following a sharp rise in the number of overdoses" and said the substance is being detected in a brown powder that is being sold as heroin in Dublin.
He said: "Preliminary laboratory analysis has confirmed that recent overdoses may be caused by heroin mixed with nitazene, a potent and dangerous synthetic opioid. These pose a substantial risk of overdose, hospitalisation and death."
Extra risk: HSE has updated the status of its warning regarding heroin overdose clusters in the Dublin Region. Analysis conducted by Forensic Science Ireland (FSI) confirms trace amount of a nitazene type substance identified in brown powder associated with a Dublin overdose. pic.twitter.com/Ez8jy294vA
— HSE Ireland (@HSELive) November 10, 2023
Dublin City Council has been involved this evening in flashing this urgent HSE message around the city on screens and tomorrow posters will be put up on windows around the city
The HSE says it is safer not to use drugs at all.
It added that naloxone is available free from every Dublin Addiction Service and temporarily reverses the effects of opiate-type drugs like heroin, keeping the person alive until emergency services arrive.
It said to avoid new batches of heroin, avoid buying from new suppliers. and avoid trying new batches or new types of drugs.
Contact the HSE Drug and Alcohol Helpline on 1800 459 459.
