Police have issued an "urgent warning" as two men collapsed after taking a so-called legal high known as Annihilation.
One of the men, aged 33, is in an induced coma while the other, aged 39, needed medical attention.
Both incidents took place in Drake Street in Rochdale, Greater Manchester.
Shortly after 11am on Friday, officers were called to reports a 33-year-old man had collapsed. His friends told officers he had been taking "legal highs".
Later, police were called at about 2.20pm where the 39-year-old had collapsed.
The man is believed to have also taken a legal high before collapsing. He received medical attention at the scene before leaving of his own accord, police said.
Detective Inspector Andy Butterworth said: "Today, two men have fallen ill after taking the 'legal high' known as 'Annihilation'. The use of 'legal highs' is a worrying trend and has ended with a man in hospital in intensive care.
"I want to remind people about the potentially life threatening consequences of 'legal highs' - they may not be illegal but they definitely are not safe.
"I would urge people not to buy these so-called 'legal highs' and to consider the threat they pose to lives.
"If family or friends find any 'legal highs' please dispose responsibly or hand in to police."
Anyone with information about where this drug may have come from should contact police on 101 as soon as possible, or the independent charity Crimestoppers on 0800 555 111.
PA
