DRUG users may be at greater risk of harm from abusing so-called 'legal highs' than they are from cannabis, cocaine or ecstasy, according to new research.

Scientists from the UK, Italy and the USA have conducted some of the first research into the physiological and psychological effects of novel psychoactive substances (NPS) such as 'spice', a cannabis substitute which burst onto the UK drug scene around eight years ago.

Read more: Doctor warns of horrific effects of legal highs

They found that many of them have worse health impacts than their more well-known counterparts, such as cannabis, cocaine, and ecstasy.

Professor Colin Davidson, who is leading the research at the University of Central Lancashire, said: “We have found that most legal highs examined, from a variety of different drug groups, have potentially dangerous side effects and may be even more dangerous drugs than those which they have been designed to replicate.

"This questions our drug policies, because by banning all psychoactive drugs we have created a legal high scene where we have little understanding of how to treat users and the adverse effects are not well understood.

"In addition, users will have little understanding of how to use the drug safely.”

The team's findings have been presented at the British Science Festival, which is taking place in Hull this week.

NPS have rapidly risen in popularity and, despite the misleading 'legal highs' nickname, they are neither safe nor legal, with most now banned under the Misuse of Drugs Act or Psychoactive Substances Act.

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However, they remain widely and cheaply available on the internet.

Professor Davidson added: “If we are to medically treat these users to the best of our ability then we need to know the pharmacological effects of these drugs.

"If we can determine how they work, then we have a better chance to treat abusers who often turn up in A&E.

"We can also use this evidence base to prioritise educational and legal resources.”

Poly-drug use makes the study of the short and long-term effects of NPS in humans difficult.

With the scientific literature focusing mostly on more traditional drugs of abuse, the study of these substances and their health effect is a neglected area of research.

Dr Hazel Torrance, head of the Forensic Toxicology Service at Glasgow University's School of Medicine, Dentistry and Nursing, said: “We have sporadic clusters of problems with NPS drugs which can have major implications in terms of harms (both short and long-term) and deaths, but the classic drugs of abuse are still the ones causing the most damage to society.

"The Psychoactive Substances Act had a positive effect on the availability of NPS on the high street and on the internet, but the illicit drug market has not reduced. Some might say the illicit drug market actually increased the purity of drugs like cocaine and ecstasy tablets to compete against the NPS.

"The other NPS which are of major concern are the synthetic cannabinoids, which seem much stronger in their effect than cannabis (THC), and are a particular problem in prisons.

"Whilst we’ve not had a huge number of fatalities, there is a big concern about the mental health implications of using these drugs, put together in a prison setting and there are big concerns for individual’s safety.”

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NPS have had a substantial effect on the Scottish drug scene, however there has been a sharp reduction in the use of NPS and related hospital admission since the law changed in 2016.

The National Drug-Related Deaths Database for Scotland highlights, meanwhile, that drug-related death are on the rise since 2015, with heroin, methadone and increasing poly-drug use most often involved.

Dr Torrance added: “The one NPS potentially having some kind of impact is Etizolam, a benzodiazepine like Diazepam.

"Scotland has an unusual relationship with benzodiazepines, which is different to the rest of the UK. In the last few years, Diazepam has been replaced by Etizolam in the drug-related deaths.

"There has however never been a death with only etizolam. All the deaths have multiple drugs, and the number of drugs included in each case is increasing.”