When the legal high mephedrone hit Tayside around April 2009 mayhem followed, says Inspector Wendy Symington, Tayside Police's drugs co- ordinator.
The volume of reports from schools and the voluntary sector about the drug's ever-increasing popularity was "alarming".
Also known as "bubbles", "drone" or "meow meow", mephedrone offered effects similar to ecstasy and cocaine, but it was cheap and sold legally on the internet and in head shops (retail outlets specialising in drug paraphernalia) as plant food.
Little or no information was available, however, about the short and long- term effects or dangers of the drug. There was the potential for "a lot of very unwell people, if not dead people", she says.
In the end, only four deaths in Scotland were attributed last year to mephedrone, two in the east and two in the west.
Even though the police had limited powers to deal with the drug, because it was legally available, they worked hard with their partners in health, schools and the voluntary sector to get the message out that "legal" did not mean safe.
Education was at the heart of their approach. But they also used legislation ranging from advertising and trading standards to health and safety to enable them to take action, says Detective Superintendent Alan Cunningham, head of investigation services at the Scottish Crime and Drug Enforcement Agency (SCDEA).
"If our intelligence told us retailers were selling substances clearly marked `not for human consumption' for that purpose, we encouraged them to take a more ethical approach to marketing and selling these products."
On 17 April, mephedrone was banned and categorised as a class B drug; as a result, availability fell and seizures by police plummeted.
Inspector Symington, however, has no doubt that another mephedrone will emerge. "Selling legal highs is very lucrative - a real money-spinner - and I fully expect that somebody at some point will come up with something as attractive as `bubbles'," she says.
Legislation alone will not eradicate these drugs; good-quality substance misuse education is as vital as ever, says Detective Superintendent Cunningham.
"Legislation and banning are important because they highlight the dangers, but where someone works to circumvent the law, we need to act on the supply and demand sides of the equation," he warns.
From 2008-09 the number of new drugs emerging in Europe almost doubled from 13 to 24 - the largest-ever number reported in a single year, according to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA), which has been responsible for monitoring new drugs and issuing early warnings since 1997.
By November last year, the 2009 record figure of 24 new substances had already been exceeded, with 31 new drugs identified (see graph).
The continuing appearance of legal highs like mephedrone was highlighted as "a challenge" last year in the centre's annual report.
Where a wall is put up to reduce supply, the drug pushers are simply developing something different, says Detective Constable Kenny Cameron, drugs strategy officer with the SCDEA.
Teachers, who may be among the first to hear about the latest trends, should not dismiss legal highs as harmless, says Austin Smith, policy officer at the Scottish Drugs Forum. Neither should they be fooled by the often innocent and comical names like Jolly Green Giant Granules, he says.
"Teachers with some substance use experience might think of legal or natural highs as rubbish drugs because that's what they were 20 years ago. But these are powerful drugs and must be taken seriously," warns Mr Smith.
The term "advanced legals" is used by some to highlight the difference between the usually herbal-based legal highs of old and the new, manmade legal highs which are proving to be a viable alternative to street drugs.
Mr Cameron prefers the label "psychoactive substances" to legal high. The word "legal" suggests the drug is innocuous, which is far from the truth, he stresses, and test purchases of so-called legal highs have demonstrated that, in spite of the label, they may contain any number of illegal substances.
Much of the danger surrounding legal highs arises because users don't know how to take them or what a safe dose looks like, continues Mr Smith. Traditionally a young person starting to use drugs would have been initiated by experienced users, but new substances mean experimentation. The younger the user, the more reckless they seem to be.
Tayside Police conducted a study into mephedrone use involving 1,006 students, 349 of whom were schoolchildren, which was published in the general medical journal QJM in July.
The study showed that use of mephedrone, before it became illegal, was "common". Of those who had used mephedrone, only students aged under 21 reported using it daily; the highest daily use was 11.1 per cent among the 13 to 15 age group.
It is not necessarily the "bad kids" who take legal highs, warns Mr Smith. "It's more likely to be the outgoing and experimental kids with a bit of extra cash and access to a computer."
Youngsters using such stimulants might be tired, suffer from mood swings and have trouble concentrating, says Mr Smith.
However, rather than relying on these warning signs, which could arguably apply to any teenager, or evidence that their children are starting to hang out with the wrong crowd, parents should be monitoring internet use, he says.
The internet is where legal highs are sold and where they are marketed, agrees Mr Cameron.
A search for English-language online mephedrone shops, conducted in March 2010, showed that at least 77 websites were selling the substance. Most of these were shut down following the UK banning of mephedrone and other synthetic cathinones.
However, it can take up to a year for a new drug to be classified, Mr Cameron says. He is looking forward to the introduction of 12-month temporary bans on suspected substances, announced by the UK Government in August.
But legislation is only half the battle, as Detective Superintendent Cunningham points out. Mephedrone might be an illegal high now, and its use might have plummeted, but it has not disappeared.
ALCOHOL STILL TOP FOR TEENAGERS
Crew 2000 in Edinburgh is the foremost Scottish drug education and public health body dealing with legal highs and psycho stimulants.
When it comes to adolescents and mind-altering substances, alcohol almost always tops the list, with cannabis the drug of choice, says operations manager Carla Ellis.
According to the Scottish Schools Adolescent Lifestyle and Substance Use Survey (Salsus), published in 2009, 11 per cent of 13-year-olds had drunk alcohol in the past week, as had just under a third of 15-year-olds.
Interestingly, 3 per cent of 13-year-olds reported taking drugs in the last month, compared with 13 per cent of 15-year-olds. By far the most common drug taken was cannabis.
The survey contained no data on legal highs. However, the latest Salsus report, set to be published later this year, will contain information on legal highs, including mephedrone, BZP, GBL or GHB and "spice".
HIGHS AND LOWS
The term "legal highs" encompasses a wide range of products, from herbal mixtures to synthetic or "designer" drugs and "party pills", which are used in different ways (smoked, snorted, ingested). These products can be marketed as room odourisers, herbal incenses or bath salts, though they are intended for a different use.