The Health Service Executive has issued a warning to people in Cork about a drug that looks like cocaine but is up to eight times more potent than heroin.
The warning follows the death of 16-year-old Michael Cornacchia at his home in the city yesterday following a suspected drug overdose.
A post-mortem examination has been carried out on his body, but it is understood toxicology tests will be required to confirm the exact cause of death.
Gardaí have analysed a sample of a substance found following the discovery of the teenager's body and have confirmed that it is the synthetic drug known as U-47700, or by its street name U-4.
The drug was first recorded in Tennessee in the United States in June 2015, and has been linked to at least 50 deaths in 10 US states.
It is the first time the drug has been recorded in this country
The HSE has issued a warning to drug users not to take the drug if they suspect it may be U-4 and to ensure that they have a friend with them who can raise the alarm if they get into difficulty if they do take the drug.