top of page

Substance Information

Cannabis is the most widely-used illegal drug in Britain. According to the Home Office Crime
Survey for England and Wales 2015/16,

6.5% of adults aged 16 to 59 used it in the preceding ye
ar (around 2.1 million people)


Among younger adults aged 16 to 24, cannabis was also the most commonly used drug, with
15.8% having used it in preceding year (around
975,000 young adults).

DSM-5 Definition of Cannabis Use Disorder

  • Cannabis is often taken in larger amounts or over a longer period than was intended.

  • There is a persistent desire or unsuccessful efforts to cut down or control cannabis use.

  • A great deal of time is spent in activities necessary to obtain cannabis, consume cannabis, or recover from its effects.

  • Important social, occupational, or recreational activities are given up or reduced because of cannabis consumption.

  • Cannabis consumption is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by cannabis.

  • Tolerance, as defined by either a need for markedly increased cannabis to achieve intoxication or a desired effect or a markedly diminished effect with continued consumption of the same amount of the substance.

  • Withdrawal, as manifested by either the characteristic withdrawal syndrome for cannabis or cannabis is taken to relieve or avoid withdrawal symptoms.



The cannabis plant produces many (over 113) known chemical compounds
referred to as
cannabinoids. The 2 main groups that are the most widely
used are THC and CBD.


Tetrahydrocannabinol (THC ) is the main compound that gives the euphoric
feeling or ‘high’ that attracts most users to the drug. Prolonged exposure,
particularly from a young age can accelerate various mental illnesses and
psychotic episodes. Regular and even occasional use can also cause feelings
of anxiety, suspicion, panic and paranoia


Cannabidiol (CBD) is closely associated with more therapeutic uses of
cannabis and is known to counteract cognitive impairment associated with the
use of cannabis. It is also credited in treatments for various medical conditions
and health. A deeper understanding of cannabinoids can be found at the
Wikipedia website here.


Tobacco and cannabis share some of the same hazards. Smoking cannabis has been linked to lung diseases like tuberculosis and lung cancer. Health effects for smoking tobacco and/or cannabis are well documented here.


Possession of Cannabis is illegal and can lead to arrest. As a class B assigned drug this may result in a caution, a fine or even jail. Details of current UK penalties on all illegal drugs can be found here


Further information on cannabis can be found at the Talk to Frank website here

or the NHS Choices website here  

or the Royal College of Psychiatrists website here.




Spice or Synthetic cannabinoids refer to a growing number of
man-made mind-altering chemicals that are
either sprayed on dried, shredded plant material so they can be
smoked (herbal incense) or sold as liquids to be vaporized
and inhaled in e-cigarettes and other devices (liquid incense).
Spice was a brand name that was briefly sold legally in the UK
but is currently illegal under the

Psychoactive Substances Act 2016

Other brand names include, Black Mamba, K2,
Annihilation, Clockwork Orange, Exodus
and  Devil's Weed.

Spice may have a similar appearance to weed but has much more extreme and disturbing effects. Spice is often referred to as the Zombie drug and a relatively small amount can produce adverse effects that may require hospitalisation. The use of Spice has contributed to serious harm and death.

Further information on Spice can be found here

22 Stories You Should Read Before Smoking Spice

Science behind the drug

Legal Highs

Legal Highs or Novel psychoactive substances

(NPS) are newly used designer drugs also known as "internet

drugs" or "research chemicals" potentially posing similar health

risks to classic illicit substances.


Although the use of novel psychoactive substances mostly

produces minor or moderate poisonings, serious

complications can occur and addiction rates are similar

or in many cases stronger than the mimicked street drug.

Issues of inconsistent quality and a lack of reliable

source base chemical identification can produce mixed and

dangerous results.

NPS types tend to be grouped in the same classes as the mimicked drug.

Stimulant-type drugs – these drugs mimic substances such as amphetamine, cocaine and ecstasy and include BZP, mephedrone, MPDV, NRG-1, Benzo Fury, MDAI, ethylphenidate.

Downer’/tranquiliser-type drugs – these drugs mimic tranquiliser or anti-anxiety drugs, in particular from the benzodiazepine family (benzos) and include Etizolam, Pyrazolam and Flubromazepam.

Hallucinogenic drugs – these drugs mimic substances like LSD and include 25i-NBOMe, Bromo-Dragonfly and the more ketamine-like methoxetamine.

The Scottish Drugs Forum carried out a survey of drug services in 2013
 which summarised some of the key harms during intoxication and comedown:

  • Overdose and temporary psychotic states and unpredictable behaviours;

  • Attendance at A&E and some hospital admissions;

  • Sudden increase in body temperature, heart rate, coma and risk to internal organs (PMA);

  • Hallucination and vomiting;

  • Confusion leading to aggression and violence;

  • Intense comedown that can cause users to feel suicidal.

  • Use was also associated with longer term health issues:

  • Increase in mental health issues including psychosis, paranoia, anxiety, ‘psychiatric complications’;

  • Depression

  • Physical and psychological dependency happening quite rapidly after a relatively short intense period of use (weeks)

Further information can be found on the Talk to Frank website here


Detailed information can be found here

Wikipedia entry on Designer Drugs here

Guidance on the Clinical Management of Acute and Chronic Harms of Club Drugs and Novel Psychoactive Substances

Significant Research

Research found that those who had used mostly ‘Skunk’-like (high potency THC) cannabis were twice as likely to be diagnosed with a psychotic disorder if they had used it less than once per week, nearly three times more likely if they used it at weekends, and five times more likely if they used it every day. The same was not true for Hash, which did not appear to increase the risk regardless of the amount smoked.
“Proportion of patients in south London with first-episode psychosis attributable to use of high potency cannabis: a case control study” Lancet Psychiatry. 2015.
Di Forti, M. Marconi, A. Carra, E. Fraietta, S. Trotta, A. Bonomo, M. Bianconi, F. Gardner-Sood, P. O’Connor, J. Russo, M. Stilo, S. Marques, T. Mondelli, V. Dazzan, P. Pariante, C. David, A. Gaughran, F. Atakan, Z. Iyegbe, C. Powell, J. Morgan, C. Lynskey, M. Murray, R


Research suggests that increasing the level of CBD in cannabis reduces the problematic effects of THC, it does not seem to impact on the feeling of being ‘stoned’ or high from cannabis. Multiple studies have shown that high doses of CBD do not change the experience or pleasurable effects of THC.

Also, exploring the effect of CBD in cannabis has shown that, when it is administered alongside THC, it can significantly reduce problematic effects both cognitively and psychologically.

When administered in isolation, THC can induce cognitive impairment and psychotic-like symptoms, but when given alongside CBD, research has shown that these effects significantly diminish.
“Can we make Cannabis safer?” Lancet Psychiatry. 2017.
Englund, A. Freeman, T. Murray, R. McGuire, P.


In a study carried out by Karniol et al, volunteers were given either a high dose of THC or both THC and CBD together. Those who received both THC and CBD together found the psychological reaction of THC to be significantly reduced.
“Cannabidiol interferes with the effects of delta 9- tetrahydrocannabinol in man” Pharmacol. 1974; 28: 172–77.'
Karniol, IG. Shirakawa, I. Kasinsk, N. Pfeferman, A. Carlini, E.


A hair sample study by Morgan et al also showed a similar link between THC and CBD, finding that those who tested positive for both THC and CBD in their hair had far fewer psychotic-like effects, than those who tested positive just for THC.
“Effects of cannabidiol on schizophrenia-like symptoms in people who use cannabis” Br J Psychiatry. 2008; 192: 306–07.'
Morgan, CJ. Curran,HV.



The vast majority of street cannabis now contains high THC levels and very little CBD to mitigate its problematic effects. This trend appears to be having a direct impact on the number of people who present for help in drug treatment.
“Why did cannabis treatment presentations rise in England from 2004/05 to 2013/14?” Drug and Alcohol Today. 17(4). 2017'
McCulloch, E.


Hospital psychiatric units have also experienced an increasing number of cannabis presentations over the past ten years. In 2015/16, there were 1606 admissions to hospital psychiatric units for cannabis-related mental health or behavioural problems – a 22% increase compared to 2014/15, and more than double the level since 2006/07
“Statistics on drug misuse, England” NHS. 2017


In the past ten years, there has been a 64% increase in the number of individuals who have accessed drug treatment services for their cannabis consumption in the UK – with 31,129 adults seeking support in 2016
“European Drug Monitoring Centre for Drugs and Addiction, United Kingdom drug report 2017”

With 31,129 cannabis consumers in treatment, this accounts for around 190,000 individuals who are consuming cannabis problematically but not accessing treatment.
“Statistic on drug misuse” UK Government. England. 2016

Since 2010, cannabis arrests in the UK have fallen by almost 50%, cautions for possession by 48% and the total number of people charged by 33%.
“Drug Misuse: Findings from the 2014/15 Crime Survey for England and Wales” 2015'




Street Lottery: Cannabis Potency and Mental Health (18th October 2017)


The science of high-potency cannabis: BBC Newsbeat (22 Aug 2017)

Cleaning up cannabis: Groups seek standards to ensure safety and quality(Volume 95 Issue 45 |pp. 27-28-Issue Date: November 13, 2017)

scra compounds
spice & rizlas
various legal highs
Significant Research
Legal Highs
bottom of page