Police are working to track down the suppliers of illicit drugs after seven people were hospitalised in Auckland over the weekend.
Two people were rushed to hospital from a brothel yesterday after ingesting what was believed to be the drug GHB.
Ambulance, paramedics and the Fire Service were called to Femme Fatale gentlemen's club on Wellesley St, central Auckland, about 8.15am.
St John Ambulance spokesman Robbie Walker said a woman was in a critical condition and a man was in a serious condition when they were transported to Auckland City Hospital.
While investigating the pair officers discovered there had been a rash of other hospitalisations in similar circumstances, prompting "immediate concern" and a wider investigation.
Detective Senior Sergeant Marcia Murray said five women were also taken to hospital for treatment after consuming "an unconfirmed illegal substance" in the past 48 hours.
Ms Murray today issued a stark warning of the "life-threatening" dangers of taking drugs, including GHB, or Gamma-Hydroxybutyrate Acid.
GHB is a class B drug which has a number of side effects including sweating, loss of consciousness, vomiting and hallucinations.
"We do not yet know if there is anything linking the different cases but we are seriously concerned at the number of people who have been hospitalised and want people to think twice before they take illicit drugs," she said.
"The consequences of taking illegal substances can be life-threatening and we want people to recognise the dangerous risk they are taking."
Ms Murray said they had ordered toxicology tests to confirm the drugs, and would be further speaking to those hospitalised today.
"We don't have confirmation yet of what all these people have had. But hopefully we will get the information that will enable us to analyse where these substances came from," she said.
"After a thorough investigation we can't count out that there may be charges laid."
Police urged people to seek urgent medical attention if they had taken a drug, because a situation could quickly change for the worse.
"If you are taking substances where you don't know where it is from or what it contains, you are taking a very serious risk with your health and you are putting your life at risk," Ms Murray said.
"We realise this is the time of the year when people are out having a good time but we want everyone to stay safe."
A woman answering phones at Femme Fatale last night said she had no comment.
Auckland Hospital emergency medicine consultant Dr Mike Nicholls said staff had noticed an "unusually frequent" presentation of comatose people thought to be from illicit substances.
"It did seemed to be high -- we haven't tallied up the numbers yet but it was noted by senior emergency staff that there was an increase compared to recent holiday periods," he said.
"We had some very unwell people."
Those affected by the drugs were comatose, and some suffered seizures, which could be life-threatening if support wasn't on hand.
"Obviously people want to have a good time but it potentially is dangerous to be taking unknown substances."
The doctor said the emergency department did not test which drugs patients had taken initially, as it took too long.
"Often they don't know, and their friends don't know either, so we just have to treat what's in front of us."
"We ask that people are vigilant in cautious if they are taking drugs, and preferably that they don't do it at all."