What is legal high mephedrone?
Clubbers may be switching from ecstasy and cocaine to the powerful legal high mephedrone, according to new research.
Little is known about the powder, which has gone from nowhere to fourth position in a study of clubbers' drug taking habits.
What is mephedrone?
Mephedrone is sold as a white powder which is usually snorted in a similar way to cocaine.
It is also found in capsules and pills or can be dissolved in a liquid. In very rare cases it can be injected.
What else is it known as?
As a relatively new drug, mephedrone has a whole host of street names including meph, 4-MMC, MCAT, Drone, Meow and Bubbles.
The chemical might also appear as an ingredient in other legal pills and powders, possibly without the actual name appearing on the packaging.
Is it anything to do with another drug called methadone?
Both have similar sounding scientific names but are completely different substances.
Methadone is a pharmaceutical drug typically used as a very strong painkiller or to treat heroin addicts.
Mephedrone is a recreational drug with effects similar to amphetamines and ecstasy.
What are the intended effects of taking it?
Mephedrone is often described as a mix between ecstasy and cocaine. Users say they feel more alert, confident and talkative.
Like cocaine, the affects appear to last around an hour before wearing off.
And the side effects?
A recent survey for the dance magazine Mixmag found that 67% of mephedrone users reported excess sweating; 51% headaches; 43% heart palpitations; 27% nausea; and 15% cold or blue fingers.
Most of those side effects are common with other stimulants like ecstasy and cocaine.
Other anecdotal reports suggest heavy use can lead to paranoia, hallucinations and serious panic attacks.
Similar psychotic effects have been reported with heavy amphetamine use.
How safe is it? Any long term dangers?
The official line is we just do not know.
Many other illegal drugs, including amphetamines and ecstasy, were first developed as medicines. It means scientists have conducted tests and have some idea of the harm they can cause.
Mephedrone does not have that scientific background and was developed in backstreet laboratories with no human testing so the long term effects are unknown.
Les King, who was leading research into mephedrone for the government before he resigned recently told Newsbeat: "Chemically it is closely related to amphetamine and ecstasy but doesn't seem to be as potent.
"On the surface that would make it less harmful but any benefit could be negated because users are taking larger amounts to get the same effect.
"So all we can say is [mephedrone] is probably as harmful as ecstasy and amphetamines and wait until we have some better scientific evidence to support that."
We still don't know if mephedrone is physically addictive. Reports suggest the effects of the drug last around an hour before users feel the need to 're-dose'.
There have been reports of users snorting more of the drug than they intended and finding it difficult to stop.
But it is unclear whether this is proof of a medical addiction or a dependence or reliance on the drug which is generally considered less serious.
How is it sold?
Websites sell the drug in bags for between £10 and £15 a gram. It is also available in the same high street 'headshops' that also sell bongs and other smoking paraphernalia.
There are reports that mephedrone is starting to be sold by some street drug dealers alongside illegal substances like cocaine and ecstasy.
What's the legal situation?
As things stand, mephedrone is not controlled under the Misuse of Drugs Act. That means it currently legal to buy and be in possession of the powder.
The legal position around selling it is more complex. It is against the law to sell, supply or advertise the powder for human consumption under the Medicines Act.
This is why most websites label the drug as a 'plant feeder' or 'research chemical' and 'not for human consumption'.
It also means a user could be breaking the law if they buy mephedrone in bulk and sell it to friends on the understanding it is to be taken as a recreational drug.
Mephedrone is already illegal in Israel, Denmark, Norway and Sweden.
Is it going to be made illegal here any time soon?
On March 29 the government's drugs advisors recommended Mephedrone be made illegal. They think it should be a Class B drug - so the same as cannabis.
An EU agency, the European Monitoring Centre for Drugs and Drug Addiction, also says it is "following closely" the growth of mephedrone.
It could produce its own report on the health risks which the UK government could then use as a blueprint to speed up legislation to outlaw the drug.
That process would take at least six months and any recommendations would then have to be incorporated into European and British law.