Last Updated:

January 30th, 2026

Legal high addiction

“Legal highs” appeared online and in head shops in the late 2000s, marketed as plant food or research chemicals to sidestep drug laws. Though the Psychoactive Substances Act 2016 banned their production and sale, the misnomer “legal highs” has stuck. These new psychoactive substances (NPS) were designed to mimic illegal drugs like cannabis, ecstasy, and cocaine, but “legal” never meant safe. Deaths involving NPS in England, Wales, and Northern Ireland increased by 222% after the 2016 ban, and the drugs remain entrenched among homeless populations and in prisons, where they cause devastating harm.

man suffring form Legal high addiction

What is legal high addiction?

Legal high/novel psychoactive substance addiction is compulsive use of synthetic substances despite mounting harm to your health and stability. NPS abuse often begins with curiosity or the belief that these substances are legal or safer than street drugs, but neither is actually true.

Legal high dependence creeps in as your brain adapts to the powerful chemicals, and this causes withdrawal if levels of the NPS in your system drop. In some cases, the withdrawal symptoms can be as rough as drugs like heroin, so you can’t stop because it makes you feel incredibly sick.

If you keep using, legal high addiction takes hold, and obtaining and using NPS has become the centre of your life. Addiction means you continue despite psychotic episodes, health scares, hospitalisations, or homelessness, and professional support is needed to stop.

Understanding legal high addiction statistics

The Crime Survey for England and Wales found NPS use has fallen in the general population, dropping from 0.5% to 0.3% among adults aged 16-59 in the year ending March 2025. However, this masks the reality in vulnerable populations, such as those sleeping rough, in prison, or struggling with mental health problems.

Research found 32% of people entering treatment for psychoactive substances (mainly synthetic cannabinoids) reported being at risk of homelessness within eight weeks. Synthetic cannabinoids were implicated in 48% of non-natural deaths among 129 prisoners in England and Wales between 2015 and 2020.

While the 2016 ban did somewhat stop casual legal high abuse among many young people, a 2024 University of Bath study found one in six vapes confiscated in English schools contained synthetic cannabinoids.

What are the most addictive legal highs?

New NPS are being created all the time to get around drug laws, and so even drugs sold under the same name can be very different substances. Three of the most common addictions to drugs previously marketed as legal highs are:

Spice addiction

Spice is a synthetic cannabinoid designed to mimic cannabis but which is far more potent. Spice has become endemic in prisons and homeless populations because it’s cheap, easy to hide, and produces a dissociation that can be a temporary escape from unbearable circumstances.
Spice addiction

Mephedrone addiction

Methidrone is a cathinone that surged in popularity around 2009-2010 before being banned in Britain. It is known as meow meow or M-cat, produces stimulant effects similar to MDMA and cocaine, and is still available, often combined with other substances.
Mephedrone addiction

Benzo Fury Addiction

Benzofuran compounds produce intense stimulant and hallucinogenic effects. It was popular in club scenes before being banned in 2014, and was linked to at least ten UK deaths between 2011 and 2012.
Benzo Fury Addiction

What are the signs of legal high addiction and abuse?

Legal high addiction can develop rapidly, and depending on the substance, you can become addicted within just a few days. But the “legal” label can make addiction denial a big barrier to getting help, as you may believe NPS are safe and non-addictive. Some telltale legal high addiction symptoms include:

  • Frozen “zombie-like” states where you’re completely unresponsive (Spice)
  • Multi-day binges without sleep, food, rest, or awareness of time passing (mephedrone, Benzo Fury)
  • Having to take more every 30-60 minutes to stay high (mephedrone)
  • Psychotic episodes or paranoia, even when you’re not high (Spice, mephedrone)
  • Taking legal highs because they may not show up on standard drug tests
  • Rapid heartbeat, overheating, sweating, or jaw clenching that won’t stop (mephedrone, Benzo Fury)
  • Nose bleeds, burns, irritation, or permanent damage from snorting (mephedrone)
  • Spending all your time and money on legal highs
  • Lying about legal high abuse to your loved ones
  • Not being able to stop, even though you have these problems

What causes legal high addiction?

Legal highs hijack the brain’s reward system with greater intensity than many traditional drugs. For example, Spice activates cannabinoid receptors far more powerfully than natural cannabis, while mephedrone and Benzo Fury flood your brain with cocaine levels of dopamine. The brain adjusts, natural sources of pleasure stop working properly, and you are stuck feeling like you need the drugs. In addition to these chemical causes, there are several risk factors for legal high addiction which include:

  • Believing NPS are safe because they were once sold legally in shops
  • Easy online availability
  • Needing drugs that won’t show up on drug tests
  • Homelessness, unstable housing, or imprisonment
  • Mental health problems, like anxiety and addiction, and depression and addiction
  • A previous or existing drug addiction
  • Trauma or chaotic early life circumstances
  • Young age, as teenagers often seek cheaper highs

woman suffring form Legal high addiction

What are the dangers and side effects of legal high addiction?

Spice has caused mass casualty incidents where dozens of people collapse simultaneously in city centres. Mephedrone has been linked to deaths from heart failure and hyperthermia. Benzo Fury’s long duration means toxic effects can persist for hours without medical intervention. Some of the most dangerous side effects of legal high addiction and abuse include:

  • Overdose causing seizures, heart failure, or sudden death
  • Hyperthermia, where body temperature rises to fatal levels
  • Psychotic episodes with hallucinations and violent behaviour that can last for days
  • Serotonin syndrome from combining legal highs with antidepressants or other stimulants
  • Heart rhythm abnormalities and cardiac arrest in otherwise healthy young people
  • Persistent psychosis, which can last for years even after you quit
  • Severe nasal damage from repeated snorting
  • Kidney failure requiring dialysis
  • Withdrawal seizures requiring hospital admission

What does treatment for legal high addiction involve?

Legal highs cause damage faster than many expect, but the longer you wait, the more complicated recovery becomes. Effective treatment will usually require:

Drug detox

A medical legal high detox is very important for managing withdrawal safely. Synthetic cannabinoid withdrawal, in particular, can be severe, involving agitation, sweating, vomiting, and sometimes seizures.

Novel psychoactive substance rehab

Drug rehab looks at all the underlying causes of legal high addiction explained above. For you, this could mean homelessness, trauma, addictions to other substances, friends who all use drugs, or mental health problems. You will first explore your addiction causes, learn how to manage them better, and then take part in relapse prevention planning to stay drug-free long-term.

Post-rehab support

Lifelong recovery often means rebuilding a collapsed life, which can include securing housing, mental health treatment, and help with benefits and employment. Rehab aftercare services and NA Meetings can provide the necessary support during that rebuilding process. If you have a co-occurring mental illness, you can also continue with medication and therapy through local services.

Finding help for legal high addiction

Legal highs can destroy lives frighteningly quickly, but recovery is possible. Even people who feared there was no hope have rebuilt stable lives with the right support. Recovery.org can answer your questions about treatment and help you find the right rehab programme. Reach out for advice and support through our contact us page.

Frequently Asked Questions

Are legal highs addictive or habit-forming?
Yes, various types of legal highs can be addictive, including Spice, mephedrone, and Benzo Fury. While people may think these are less addictive than “traditional” street drugs, their unpredictable strength and content can make them both more addictive and more dangerous.
Can legal highs cause long-term mental health problems?
Yes, legal highs can make existing mental health problems worse and trigger entirely new ones. These include long-term depression, anxiety, increased risk of schizophrenia, self-harming and suicidal thoughts, and persistent psychosis.
What is the difference between legal highs and traditional drugs?
Legal highs are synthetic substances created to mimic traditional drugs while evading drug laws. One of the biggest differences is unpredictability, as NPS vary enormously in strength and contents, and there is little research into long-term effects.

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