Synthetic cannabinoid use disorder

Synthetic cannabinoid use disorder describes the clinically significant pattern of craving, escalating use and withdrawal that develops with repeated use of synthetic cannabinoid receptor agonists, the laboratory-made compounds sold as Spice, K2 or herbal incense

Synthetic cannabinoids are structurally diverse full agonists at CB1 and CB2 receptors with higher potency and affinity than delta-9-tetrahydrocannabinol, so intoxication is more intense and more often complicated by psychosis, seizures, acute kidney injury and cardiovascular events

The disorder is not a separate DSM-5 diagnosis, and it is diagnosed by applying the DSM-5 cannabis use disorder criteria to synthetic cannabinoids, a distinction that matters because the substances are often not detected by routine urine immunoassays

Terminology and classification

• Synthetic cannabinoids are also called synthetic cannabinoid receptor agonists, synthetic cannabimimetics or designer cannabinoids, and the street names Spice and K2 refer to products rather than to a single chemical
• The DSM-5 diagnosis applied in practice is cannabis use disorder, because DSM-5 lists cannabis as a single substance class and does not create a separate code for synthetic cannabinoids
• ICD-10 codes F12.1 for harmful use and F12.2 for dependence syndrome, while ICD-11 uses 6C41.0 for harmful pattern of use and 6C41.1 for cannabis dependence, and both systems classify synthetic cannabinoids with cannabis rather than with hallucinogens
• The compounds are chemically grouped into aminoalkylindoles such as JWH-018, cyclohexylphenols such as CP 47,497, dibenzopyrans such as HU-210 and tetramethylcyclopropyl ketones, and this structural diversity explains why immunoassays and targeted mass spectrometry panels miss many analogues
• Synthetic cannabinoid use disorder is distinguished from synthetic cannabinoid intoxication, withdrawal and induced psychosis, which are transient substance-induced syndromes rather than the persistent pattern of impaired control that defines a use disorder
• The main differential at classification level is natural cannabis use disorder, followed by stimulant use disorder, alcohol withdrawal, sedative-hypnotic withdrawal and primary psychotic disorders, because the acute presentations overlap substantially

History

• JWH-018, one of the compounds most often found in early Spice products, was synthesized in 1995 by John W. Huffman's laboratory at Clemson University during research on cannabinoid receptor ligands
• Spice products appeared in European head shops around 2004, and by 2008 the K2 brand had become widely available in the United States, where emergency department visits for synthetic cannabinoid toxicity rose sharply
• The United Nations Office on Drugs and Crime launched its Global SMART programme in 2008 to monitor synthetic drugs, and the programme later documented the rapid replacement of scheduled cannabinoids with new unregulated analogues
• The United States Drug Enforcement Administration placed five synthetic cannabinoids including JWH-018 under emergency scheduling in 2011 and made the scheduling permanent in 2012, after which manufacturers shifted to other analogues
• DSM-5, published in 2013, consolidated substance use disorders into a single dimensional diagnosis and removed the abuse-dependence distinction, which is the framework now used to diagnose synthetic cannabinoid use disorder
• The United Kingdom Psychoactive Substances Act 2016 banned the production, distribution, sale and supply of psychoactive substances for human consumption, and several countries adopted similar blanket legislation as analogue-by-analogue scheduling proved too slow
• From 2023 onward, outbreaks of a synthetic cannabinoid-containing drug mixture called Kush in Liberia and Sierra Leone led both governments to declare public health emergencies, illustrating how rapidly changing products can overwhelm weak regulatory systems

Epidemiology

• In the United States the prevalence of synthetic cannabinoid use rose from 0.17% in 2021 to 0.26% in 2023, and the number of people meeting criteria for a use disorder rose in parallel
• Youth and young adults aged 12 to 29 make up the largest demographic presenting to emergency departments after synthetic cannabinoid use, and 4.5% to 13.5% of high school students in New York reported lifetime use in surveyed cohorts
• Male sex is associated with higher odds of use in survey data with an odds ratio of 2.63, age 16 to 17 years with an odds ratio of 1.99 and urban residence with an odds ratio of 1.57
• Reported prevalence varies widely between countries because surveillance systems differ, because many users do not know what they have taken and because routine toxicology does not identify most synthetic cannabinoids
• Emergency department burden is dominated by young men presenting with agitation, psychosis, seizures, vomiting, tachycardia and acute kidney injury, and intensive care admission is required in a minority with severe toxicity
• Outbreaks are concentrated in marginalised urban populations, including people experiencing homelessness and people in custody, where cheap potent products circulate and where polysubstance use is common
• Mortality data are incomplete because deaths are often attributed to trauma, sepsis or cardiac events rather than to the drug, but case series report fatal arrhythmia, myocardial infarction, stroke, status epilepticus and hyperemesis-related complications
• The epidemiology is further complicated by product substitution, so a prevalence estimate for one analogue cannot be assumed to apply to the compound circulating in the same market a year later

Pathophysiology

• Synthetic cannabinoids act as full agonists at CB1 receptors, whereas delta-9-tetrahydrocannabinol is a partial agonist, and this difference produces more intense and less self-limited receptor activation at equivalent dose
• CB1 receptors are densely expressed in the cortex, hippocampus, basal ganglia, cerebellum and brainstem, and their activation reduces neurotransmitter release at both excitatory and inhibitory synapses, producing the mixed sedative, psychotomimetic and autonomic effects
• Activation of CB1 receptors on GABAergic interneurons in the ventral tegmental area disinhibits dopaminergic neurons and increases dopamine release in the nucleus accumbens, which is the principal mechanism of reinforcement and craving
• Many synthetic cannabinoids have active metabolites, and JWH-018 metabolites retain or increase CB1 affinity, so the duration and intensity of intoxication can exceed what the parent compound alone would predict
• Some analogues also interact with non-cannabinoid targets such as serotonergic, GABAergic, glycinergic and transient receptor potential channels, which may explain serotonin syndrome, seizures and cardiovascular instability that are unusual with natural cannabis
• Chronic use produces CB1 receptor downregulation and tolerance, and withdrawal reflects the resulting rebound in autonomic and limbic activity rather than clearance of the drug itself
• Pyrolysis during smoking generates thermal degradants, some of which retain high CB1 affinity, and adulterants such as synthetic cathinones or fentanyl have been found in some products, complicating attribution of toxicity to the cannabinoid alone

Clinical features

• Intoxication typically produces tachycardia, conjunctival injection, dry mouth, increased appetite, euphoria, impaired judgement and slowed time perception, with agitation, anxiety and panic in a substantial proportion of users
• Severe intoxication can cause psychosis with hallucinations, paranoia and delusions, seizures and status epilepticus, hyperemesis, acute kidney injury with rhabdomyolysis, myocardial infarction, arrhythmia, stroke and respiratory depression
• Withdrawal begins within days of cessation and includes insomnia, sweating, headache, nausea, craving, irritability, depression, aggression, tremor and, in severe cases, fever and seizures
• Psychiatric complications include cannabis-induced psychotic disorder, anxiety disorder, sleep disorder and worsening of pre-existing depression or schizophrenia, and these can persist beyond the period of intoxication
• Gastrointestinal features include recurrent vomiting, abdominal pain and weight loss, and the pattern can mimic cyclic vomiting syndrome or cannabinoid hyperemesis syndrome
• Cardiovascular and renal complications are more frequent than with natural cannabis and include hypertension, tachyarrhythmia, myocardial ischaemia, acute tubular injury and electrolyte disturbance from vomiting

Diagnosis

• The diagnosis is clinical and applies the DSM-5 cannabis use disorder criteria, requiring at least two of eleven symptoms within twelve months, such as craving, tolerance, withdrawal, unsuccessful attempts to cut down and continued use despite harm
• A structured clinical interview should document the substance, route, frequency, amount, duration, functional impairment and comorbid psychiatric symptoms, because users often misidentify the product as natural cannabis or as an incense
• Standard urine immunoassays for cannabinoids are often negative because they target delta-9-tetrahydrocannabinol metabolites, and confirmation requires liquid chromatography with tandem mass spectrometry or high-resolution mass spectrometry
• Laboratory evaluation in acute presentations includes electrolytes, renal function, creatine kinase, troponin, glucose, blood gas and electrocardiography, because seizures, rhabdomyolysis, myocardial injury and arrhythmia are the main early hazards
• The differential includes natural cannabis use disorder, stimulant intoxication, serotonin syndrome, neuroleptic malignant syndrome, acute primary psychosis, delirium, sepsis and sympathomimetic toxicity from adulterants
• Psychosis and agitation should not be assumed to be substance-induced until infection, metabolic derangement, head injury and withdrawal from alcohol or benzodiazepines have been excluded, because these require different immediate treatment

Management

• Acute intoxication is managed with supportive care in a quiet environment, continuous monitoring of airway, breathing and circulation, intravenous fluids and correction of electrolyte and metabolic abnormalities
• Benzodiazepines such as diazepam or lorazepam are first-line for agitation, seizures and autonomic overactivity, while antipsychotics such as haloperidol or olanzapine are used cautiously for persistent psychosis once medical causes are excluded
• There is no approved medication for synthetic cannabinoid use disorder, and pharmacotherapy is symptom-directed, with anticraving agents such as N-acetylcysteine studied mainly in natural cannabis use disorder rather than in synthetic cannabinoid users
• Cognitive behavioural therapy, motivational enhancement therapy and contingency management are the best-supported psychosocial treatments, and they target craving, triggers, comorbid anxiety or depression and relapse prevention
• Withdrawal is managed with gradual reduction, sleep hygiene, hydration, antiemetics and short courses of benzodiazepines when autonomic symptoms are severe, with monitoring for seizures and delirium
• Medical complications require targeted treatment, including renal replacement for severe kidney injury, coronary assessment for chest pain or ischaemic changes, and intensive care for status epilepticus or respiratory failure
• Harm reduction advice includes using small doses, avoiding mixing with alcohol or other drugs, taking breaks to limit tolerance and never using alone, because complete abstinence is not achieved by many users
• Relapse prevention should address housing instability, peer networks, legal problems and untreated mental illness, and integrated care with addiction psychiatry, social work and primary care improves engagement more than substance-specific counselling alone

Research and controversies

• Whether synthetic cannabinoid use disorder is clinically distinct from natural cannabis use disorder or simply a more toxic route of exposure is unresolved, and the answer affects whether services need a separate treatment pathway
• The rapid turnover of analogues makes clinical trials difficult, because a study of one compound may be obsolete before recruitment finishes and because users rarely know which substance they consumed
• Evidence on long-term neuropsychiatric harm is limited to case series and cross-sectional studies, and whether repeated synthetic cannabinoid exposure causes persistent cognitive decline independent of pre-existing vulnerability remains uncertain
• Regulatory policy oscillates between analogue-specific scheduling, blanket bans and harm-reduction-oriented regulation, and there is little comparative evidence on which approach reduces use-related harm without pushing users toward more dangerous unregulated products
• Low-cost point-of-care testing and wastewater surveillance are promising tools for early detection of new analogues, and international sharing through the UNODC early warning system is likely to be more effective than any single country's laboratory capacity