A 21-year-old woman remains critically ill after taking an unknown so-called "legal high", police have said.
She was admitted to Newcastle's Royal Victoria Infirmary after falling ill in the early hours of Friday morning.
She had taken tablets, which at this stage are believed to have been bought at the Happy Chippy takeaway in Waterloo Street, Newcastle, police said.
Officers are investigating to establish exactly what drugs the woman took.
Three people aged 38, 26 and 17 who were arrested on suspicion of drugs offences have been released on police bail.
A Northumbria Police spokeswoman said the 21-year-old "remains in a critical but stable condition".
Detective Chief Inspector Ian Bentham said: "Police are also issuing advice to anyone else who may have bought legal high-type substances from the Happy Chippy not to consume them, and to contact the police.
"We do not want anyone else to become ill. If you know of anyone who has bought items from this store, please ask them to follow our advice."
Any witnesses or anyone with information is asked to contact Northumbria Police on 03456 043 043 ext 69191 or ring the independent charity Crimestoppers on 0800 555 111.