Doctors have been put on the alert for more strong heroin-related cases in Cork after two men died and two more became seriously ill.
Gardai have searched addresses in the north and south of the city and recovered some of the drugs, believed to be part of the potent batch. There is nothing to suggest it is contaminated.
One patient was taken to the Emergency Department in Cork on Friday night requiring medical treatment as a possible result of taking heroin, the health service said.
Investigations are ongoing into the cases that required hospital attention. It is possible they are linked to a strong batch of heroin which may be in circulation.
The HSE South has warned medical professionals in the region to be alert for patients presenting as a result of heroin misuse. Community and voluntary groups working with drug users have also been alerted and police are aware of the matter.
Health professionals have been reminded to be vigilant and the public advised that taking drugs carries serious health risks.