A 24-year-old woman is believed to be the latest victim of "party drug" mephedrone, police said.
The woman, who has not been identified, was found dead at an address in Norton, near Malton, North Yorkshire, by a friend.
Detectives believe the woman may have taken mephedrone, also known as M-Cat or miaow miaow.
This latest tragedy follows the deaths of Louis Wainwright, 18, and Nicholas Smith, 19, who died in Scunthorpe last week following a night out.
North Yorkshire Police issued a stark warning about the dangers of the drug as it made an appeal for anyone who may have seen the victim in the last couple of days to come forward.
Detective Chief Inspector Nigel Costello said: "Although at this time it cannot be determined whether mephedrone is present within the deceased's system or whether the drug played any part in her death, the police would like to warn people about the use of the drug and its potentially lethal consequences.
"If you have used this drug and feel unwell then you should seek urgent medical assistance. If you possess this supposed legal substance then please hand it to the police or dispose of it safely.
"Although mephedrone is currently not classified as an illegal drug, people need to know that this substance is very dangerous and it is important that anyone who has taken it contacts their local GP or hospital immediately."
A post mortem examination would be held in the next few days and a report will be prepared for the coroner.