Two men remain critically ill in hospital this morning after they consumed an unknown drug at a house party in Waterford early yesterday.
A total of 15 people fell ill after the 21st birthday party in the Ballybeg Square area.
Three people were initially in a critical condition, but one improved during the day and was said to be stable last night.
Gardaí are awaiting the results of toxicology tests on a white substance recovered from the house.
A 25-year-old man was arrested yesterday in connection with the incident and is still in garda custody this morning.