A man has been arrested after three people from Liverpool were taken to hospital when they took a so-called legal high which is a chemical normally used to clean alloy wheels.
Two men, aged 20 and 22, and a 16-year-old girl were believed to have taken a number of substances, including Geebs.
Police were called to student accommodation at Borden Court in Liverpool city centre after the three people collapsed in a communal area of the building.
All three were rushed to intensive care at Royal Liverpool University Hospital but their conditions later improved.
Merseyside Police arrested a 19-year-old man from Worsley, Manchester, on suspicion of supplying a Class C drug.
Geebs, or GBL, is legal for use in industry as a paint stripper, rust remover or alloy cleaner, but it is illegal to sell it as a drug.
Officers have searched Borden Court and an address in Lawrence Road, Wavertree, where the two men and teenager had attended a party.
Detective Superintendent Chris Green, said: "We have consulted with the Royal Liverpool University Hospital and established that if taken this substance (Geebs) can have side effects, but at the end of the day this substance is a chemical used to clean car wheels and even in small doses can kill.
"We have spoken to a number of people who were at the party at Lawrence Road but we know that there were other people who were at the party and we would like them to come forward for two reasons. The first to check that they are safe and well and secondly to see if they have any information which could help us with our inquiries.
"We will be working with universities in the city in the coming days to warn students about the dangers that drugs and chemicals can have when taken, particularly if mixed with alcohol or other substances.
"We understand that the three people involved may have taken other substances and as a precaution checks are under way to establish what those drugs were and to ensure that they have not taken drugs that are part of a bad batch."