Controversial drug mephedrone has become so popular it is being seized more often than ecstasy, according to Avon and Somerset police.
Paul Bunt, drugs strategy manager for the force, said there had been a significant increase in its use since it first appeared on the scene at last year's Glastonbury Festival.
He spoke out as it emerged that Government drug advisers could recommend a ban on so-called the "legal high", also known as M-Cat or Miaow Miaow, within weeks following the deaths of two teenagers who took the drug on a night out in Scunthorpe.
Retired inspector Mr Bunt, who sits on the Advisory Council on the Misuse of Drugs (AMCD), said: "Locally there has been a significant increase in its use and the number of seizures of it since it first came to light at Glastonbury last summer.
"It's a concern that it is replacing drugs such as ecstasy and cocaine. It also concerns us that a lot of young people see that it is not illegal and therefore think it is safe.
"But it's far from safe and there's no scientific research on it because it's such a new drug. We have evidence that people who have been treated because of its use have suffered effects as bad if not worse than those you would get from amphetamine or methamphetamine.
"In chemical terms, it is like a cousin to those drugs and could be as harmful."
Mr Bunt said that because mephedrone comes in a white powder form, it is difficult to distinguish from cocaine, amphetamine and ketamine without tests being carried out on it.
He said people needed to be educated about the dangers of the drug, which he said was widely available on the internet.
Mr Bunt said: "As a police force and with the drug agencies, we need to educate people about what they are putting in their bodies. It's advertised as a plant food which is not fit for human consumption.
"I would urge people not to be fooled by the term 'legal high'. People seem to think it has been endorsed by the Government or officialdom but it is a product which is pretending to be something it isn't."
Maggie Telfer, spokeswoman for Bristol Drugs Project, said the organisation had received calls from people who had taken mephedrone, predominantly older teenagers.
She said: "It's been around on a significant scale since last summer and we are taking helpline calls from people about mephedrone, but in small numbers."
Ms Telfer said the drug posed a greater risk to those with heart problems and affected some people more quickly than others. She said symptoms included heart palpitations and panic attacks.
Adrian Ruck, spokesman for University Hospitals Bristol NHS Foundation Trust, said three people had attended the accident and emergency department of the Bristol Royal Infirmary in the past two months after taking mephedrone.
The ACMD is to issue a report into a group of "legal highs" at the end of this month.
Ministers said they would then take "immediate action" based on the advice.
March 19, 2010
This Is Bristol
'Legal' drug mephedrone seized more than ecstasy in Bristol