Doctors are warning of the dangers of a dance-scene drug containing a potentially harmful anti-worming agent.
The drug BZP is being taken by some clubbers
Doctors writing in The Lancet medical journal highlighted the case of an 18-year-old woman who collapsed in a London club and suffered a seizure.
She had taken the drug benzylpiperazine, known as BZP, and was given emergency treatment in hospital before being discharged.
The drug was legally available over the counter in the UK until last month.
The active ingredient in BZP is piperazine, developed in the 1950s as a veterinary worm medicine.
According to the Lancet, the drug benzylpiperazine has a chemical structure similar to amphetamine.
It has now become an increasingly popular alternative to ecstasy and amphetamines and is sold under names such as Pep Twisted, Legal E, Nemesis and Euphoria.
Doctors say there is no reliable data on how many people take BZP in the UK, but according to one manufacturer 20m pills had been consumed in New Zealand with no deaths or lasting injuries.
But the doctors added that trials had shown BZP produces adverse effects that mirror amphetamines, including nausea, vomiting, rapid heart beat, high blood pressure, anxiety and agitation.
Dr Roland Staack, from Ludwig Maximilians University in Munich, Germany, said the low number of reported cases of BZP poisoning may be down to confusion with amphetamines.
"Piperazines and amphetamines are similarly marketed, consumed by the same population, and show similar pharmacological symptoms," he said.
"Therefore a piperazine poisoning can easily be wrongly diagnosed as an amphetamine poisoning."
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