Psychoactive substances in prisons

A summary of evidence relating to the use of psychoactive substances in prisons.

Increasing use of psychoactive substances in prisons presents staff with significant new challenges. However, there is a lack of published research and evidence about the effects of these substances and how to effectively reduce their use.

What are psychoactive substances?

Psychoactive substances are either naturally occurring, semi-synthetic or fully synthetic compounds. When taken they affect thought processes or individuals’ emotional state. Synthetic cannabinoids are most prevalent and particularly disruptive in prisons. Street names include spice, mamba, K2 and Exodus, but there are hundreds of others. In prisons, these substances are commonly referred to as ‘spice’.

Often, these drugs are incorrectly referred to as ‘legal highs’. Some of these substances may not be listed under the Misuse of Drugs Act 1971. But the Psychoactive Substances Act 2016 covers all other psychoactive substances. Prisoners, staff or visitors found in possession of a non-controlled psychoactive substance in a custodial setting can now face criminal charges.

How prevalent is psychoactive substance use?

In the UK, the last decade has seen a rapid growth in both availability and use. However, it is difficult to obtain exact figures. This is partly due to ever-changing use of new chemicals and modifications to compounds in an effort to evade regulation and control. UK national crime surveys in 2013-2014 found 0.6 % of the adult population in England and Wales had taken mephedrone, 2.3 % nitrous oxide and 0.5 % salvia. Estimated use amongst younger adults is higher. The group with the highest reported use are nightclub visitors. Evidence indicates that psychoactive substances are predominantly used outside prison by those who are already illicit drug users. Typically, users are young male, and those who frequent nightclubs1.

Their use inside prisons may be different and may not necessarily be used by those already using illicit drugs. Use of psychoactive substances have become a significant problem in prisons in England and Wales in recent years. The most frequently used are synthetic cannabinoid receptor agonists (SCRAs). These compounds mimic the effects of cannabis2. Some argue that their increased use in UK prisons may link to increases in violence, self-harm and death in custody. There is no hard evidence of a direct causal link. However, we do know that some psychoactive substance users, like alcohol users, while intoxicated, can become violent.

What are the effects of psychoactive substance use?

The desired positive effects include sedation, relaxation, euphoria and altered perception. Users in prison refer to it as ‘taking a holiday’ or providing a sense of ‘escape’ from prison life.

Evidence of the negative impacts of psychoactive substances on health is relatively well-established. The most commonly reported are cardiac, psychiatric and neurological. Their use may also lead to violence, homicidal combative behaviour, self-mutilation, coma and death. Commonly reported immediate effects include:

  • agitation
  • cardiovascular complications including chest pain, palpitation and collapse
  • psychosis, hypertension and seizures

How good is the evidence and what do we know about the effects of passive exposure to psychoactive substances?

More research is needed, as there are no published studies on any impact on health from second hand exposure to psychoactive substances, such as inhalation of the smoke or by-product from their use by those not using the substances themselves. In the prison context, this relates both to staff working in the prison and non-using prisoners.

Indications are that passive exposure is detectable in non-users exposed to psychoactive substances. But this has not yet demonstrated the impact that their exposure may have on non-users. There is no reliable evidence about the possible effects of passive exposure to prisoners’ use on staff and other individuals and so research is ongoing.

Why do people take psychoactive substances in prison?

There has been significant local work and research to determine the motivations behind psychoactive substance use in prisons. However, there is a lack of peer-reviewed published research, primarily because the rise of their use is so recent. The limited published research, however, indicates that motivations for their use in prison include:

  • accessibility and the low cost
  • certain types of these substances have only become detectable via Mandatory Drug Testing (MDT) in September 2016 - before that they evaded detection
  • as a coping mechanism to deal with life in prison and personal issues
  • boredom and lack of purposeful and engaging activity
  • having an addiction to psychoactive substances - this may have displaced or substituted for an existing dependency on illicit drugs or medication, or developed over time
  • believing that everyone else is doing it, thus making it more socially acceptable
  • enjoyment, for both the effects and the entertainment of spiking others

Understanding the motivations behind their use can help us to identify what strategies might help in reducing uptake. The introduction of testing may have an impact on future use and reasons for use.

What are the reported consequences of taking psychoactive substances?

The limited published research suggests that the following may result from PS their use in prison:

Addiction: regular use can create both psychological and physical dependence. Classic indicators include: intense craving, rapid tolerance (increasing daily dose to get the desired effects), withdrawal symptoms when use suddenly stops, others, including doing things to get and use psychoactive substances that might not usually occur with use of other recreational drugs. This ranges from acquisitive crime to sexual activity.

Debt: the average cost of psychoactive substances in prisons can be up to 10 times the street value. The effects of many of them are initially intense. Regular users develop tolerance which can result in their habits escalating and getting into debt with dealers.

Bullying and violence has been reported by those with related debts. Bullying type behaviour includes ‘spiking’ and giving other people ‘over-loaded spliffs’. This can be for entertainment, relieving boredom or expressing dominance.

Mental health problems related to these substances have mainly involved psychotic reactions. This is especially common among prisoners with existing mental disorders like schizophrenia.

Self-harm whilst intoxicated on or withdrawing from them. Also resulting from stress, anxiety and depression associated with related debts, bullying and violence.

How can we reduce use of psychoactive substances in prison?

There is currently limited evidence around what can be done to reduce use of psychoactive substances in prison. However, evidence on traditional drug use and behaviour change can help. This evidence can also identify what is unlikely to reduce their use. More evidence is required before we fully understand how to reduce their use in prison.

Evidence-based strategies which may help reduce psychoactive substance use:

  • encouraging new behaviour by reward or reinforcement is usually more effective than punishing bad behaviour - use of reward (more frequently than punishment) may be effective in reducing their use in prison.
  • psychosocial, cognitive-behavioural treatment programmes may be effective for prisoners with substance use challenges.
  • theories of behaviour change indicate that people need to have capacity, opportunity and motivation to change - helping people change their lives (including reducing or ceasing problematic drug use) may be achieved through small, everyday interactions - these aim to instill hope, increase purposeful activity, find meaning in work or education, enable autonomy, provide coaching in problem-solving and goal-setting.

Evidence indicates that some strategies are unlikely to help reduce their use:

Alcohol and drug awareness programmes that are purely educational are ineffective. Unless accompanied with teaching skills in self-management or behaviour change, these are therefore unlikely to help people to stop using psychoactive substances.

Interventions that use scare-tactics to deter people from using psychoactive substances.

Use of adjudications alone as deterrence/punishment is unlikely to reduce their use in the long-term. Punishment is most likely to be effective when it is delivered in a swift, severe and consistent manner, accompanied with information and viewed as fair.

Control-based interventions like drug testing are unlikely to reduce their use unless accompanied with opportunities to address drug dependency and the cause of drug use in prison.

Showing individuals themselves under the influence of alcohol or other drugs (videotape self-confrontation) does not have an impact on use. Recent research from the body worn video camera (BWVC) pilot evaluation supports this. Although not yet published, this suggests caution for showing people BWVC footage of themselves under the influence of psychoactive substances. Doing so is unlikely to result in long-term change in their use and may even do harm with some individuals.

Further reading

National Prison Drugs Strategy Ministry of Justice and Her Majesty’s Prison and Probation Service Prison Drugs Strategy (MoJ 2019)

New Psychoactive Substances Toolkit for Commissioners Public Health England. This toolkit helps local authorities and NHS England to respond to PS use and problems in their areas.

Changing patterns of substance misuse HMIP thematic report on changing patterns of substance misuse in adult prisons and service responses (2015)

New Psychoactive Substances PPO Learning Bulletin examining deaths of prisoners where the use of PS-type drugs was suspected (July 2015)

Home Office - New Psychoactive Substances (NPS) resource pack (2015)

The Drugs Wheel NPS Training Toolkits

New Psychoactive Substances in Europe short report highlights recent developments, including the growth of the market, as illustrated by seizures by law enforcement and other indicators, as well as the growing number of serious harms that are being reported as a result (March 2015)

Serious Crime Act (2015) makes it a crime to throw any object into a prison, including psychoactive substances

New Psychoactive Substances in England: A Review of the Evidence Home Office


  1. New psychoactive substances in prisons: A toolkit for custodial, healthcare and substance misuse staff. (2017)
  2. Wheatley, M., Stephens, M., & Clarke, M. (2015). Violence, Aggression and Agitation – What part do New Psychoactive Substances play? Prison Service Journal, 221, Special Edition on Reducing Prison Violence.

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This page summarises the available evidence base and is informed by independent academic peer review. It does not represent Ministry of Justice or Government policy.

Published 15 May 2019