Seven people have been taken to hospital after taking the sleeping medication Zopiclone, prompting concerns over a “potential contaminated batch.”
Cleveland Police said it had received reports on Friday of the adults being taken to North Tees General Hospital in Stockton-on-Tees, County Durham.
The force is also investigating the death of one man thought to have taken Zopiclone.
The force said: “Officers are warning drug users of a potentially contaminated batch which could cause significant illness or lead to an overdose.”
Zopiclone, usually used to treat insomnia, takes around an hour to work and helps users to fall asleep faster and stop waking in the night.
The drug is usually taken as a tablet but doctors can order it in liquid form.
It triggers a calming chemical in the brain called gamma-aminobutyric acid (GABA), according to the NHS website.
The NHS warns against drinking alcohol after taking the drug because it can induce a “deep sleep where you find it difficult to wake up.”
Users can become dependent on Zopiclone, the NHS said, and it is prescribed for just two to four weeks because it becomes less effective as the body gets used to it.
