A passer-by who went to the assistance of people who are thought to have taken 2C-B in Cork has described arriving at the scene.
He said that he saw blood on the walls and carpet at the rented house on Pouladuff Road.
Five men and a woman, aged from 18 to 37, were rushed to Cork University Hospital.
An 18-year-old was remains critically ill in hospital while three others are in a stable condition.
According to the Irish Examiner, the alarm was raised at around 4am when a couple passing the house became concerned when they saw at least one man dancing naked and apparently hallucinating on the street.
Speaking to Neil Prendeville on Cork’s RedFM, he said it was "one of the scariest and most surreal nights of my life".
He said: “I was walking past late last night and heard crazy shouting at a house.
“So me and a friend looked in the window to see is everyone OK.
“The bedroom was covered in blood, walls, floor, bed and even curtains.
“We shouted in to see is everyone OK. A man arrived at the window clearly on drugs and in a state of shock.
“We asked is everyone OK. He replied: ‘Yes, everything is fine’.
“So we said there is blood everywhere someone must be hurt can we check to make sure no one is hurt.
“He said yes and opened the door.
“When we went in it was like a scene from CSI - blood all over the walls, floors, couches and a man and a woman naked covered in blood shouting and screaming badly hurt and clearly in a state of dementia.
“The man was smashing the house up, blood was everywhere. The house was destroyed.
“There was a man on the floor in cardiac arrest with major breathing problems and the man who let us in sitting on the chair in shock.
“In shock, me and my friend took control of the room.
“My friend started helping the man in cardiac arrest on the floor.
“I had to control the room to let my friend help the man on the floor in safety.
“It was surreal.. a naked man and woman dancing naked on the chairs as a man was having cardiac arrest on the floor.
“I was the man who left the guards and paramedics into the house.
“It was surreal.. . myself my friend, gardaí and paramedics were all in shock.
“I have huge respect for the Gardaí and paramedics who were on the scene. I made a statement with the gardaí last night and will be doing so again today.
“Whatever drugs those people were on last night in Pouladuff Road was scary.
“They didn’t even know they were covered in blood and badly hurt, they didn't even know there was a man dying on the floor.
“I haven’t slept a wink all night, I’m still in shock to be honest.
“These people did not seem like bad people just like students out partying which is the most worrying thing about this new drug and its side effects.
“It’s really scary stuff and we need to make everyone aware of its dangers.
“Everyone in the house was rushed to hospital. I have never seen so much blood.”
He added: “Please share the message and lets warn Cork about the dangers of this new drug.”
The HSE has issued a warning about the danger posed by the pills.
"These drugs can be sold in tablet powder or liquid form and are consumed at parties or clubs for their stimulant, mood altering and in some cases, aphrodisiac effect," said a HSE statement.
"However, it is generally reported that these drugs can have serious side effects both from a psychological and physical viewpoint.
"Such side effects include paranoia, hallucinations (both auditory and visual), gastrointestinal effects and kidney problems.
"Young people are advised that there is no quality control on these drugs.
"There are problems with purity and contaminants, and there is no way of checking that what is purchased or consumed is the intended substance.
"Given the serious side-effects experienced by the young people in Cork, the HSE Addiction services are issuing a warning about possible contaminated ‘party pills’ and advise people not to consume any unknown substances that they are offered at this time."