Police have renewed warnings about party drugs sold as ecstasy after analysis of six different pills linked to recent drug-induced overdoses did not identify a specific reason for the alarming spike in health problems.
More than 20 people in Perth and the South West were treated in hospital after recreational drug overdoses around New Year's Eve.
Doctors at Fremantle Hospital have previously revealed that patients they saw needed treatment for paranoid and delusional behaviour, aggression and psychosis.
Overdose patients who were willing to talk to police said they had taken a substance they believed was MDMA or ecstasy.
Police said there were consistent references to the same six pills - sold as Batman, Blue Batman, Light Blue, Sandy, Cookies 'n' Cream and Lightning Bolt.
Organised crime squad detectives had several seized pills analysed but revealed results had not indicated any specific reason for the health problems.
They said it was possible those people had taken other MDMA pills, or had bought copies of the pills they had named and those had contained other chemicals.
Det-Insp. Chris Adams said the analysis of seized pills had highlighted their varying purity and ingredients.
Tests of two pills sold as the same product to unsuspecting buyers found one contained dangerous illicit chemicals and the other contained only caffeine.
Police said they have previously found washing powder, chalk and even crushed glass in substances sold as party drugs.
"No illicit drugs are safe to use and what we saw over New Year's Eve has us even more concerned," Det-Insp. Adams said. "Even if word gets around on the streets that a drug is 'safe' to use, you can never be sure that the drug you are buying is not a copy . . . you won't know what has been put in the pills you are taking."
He urged anyone who had bought illicit drugs, particularly MDMA pills such as those pictured, to dispose of them.