Health authorities have issued an alert about a contaminated batch of cannabis resin that may be circulating in the northeast.
The Health Service Executive issued the warning after two women in Co Louth became critically ill after taking cannabis that may have been mixed with another substance.
The women, both in their 20s, are being treated in the Intensive Care Unit at Our Lady of Lourdes Hospital in Drogheda.
One of the women became ill on Monday night.
It is understood that she has not regained consciousness since being admitted to hospital and is on a life support machine.
The second woman became seriously ill in the early hours of yesterday morning.
Tests are being carried out on an amount of the drug seized when gardaí raided two houses in the town.
Garda Superintendent Gerry Smith of Drogheda Garda Station said: "We are concerned that other people who use cannabis may suffer the same effects."
HSE Addiction Services in the northeast issued an alert to service users and community groups working with drug users.
The HSE has advised that a contaminated batch of cannabis resin appears to be circulating in the Cavan/Louth/Meath area and that reports have been received of unusual side effects.
Andrew Ogle of HSE Addiction Services said: "If someone gets into difficulty after consuming a substance it is critically important to get help immediately by calling the emergency services."