A systematic review of 49 studies found synthetic cannabinoids cause significantly more severe neurological and cardiovascular complications than natural cannabis, including seizures, altered consciousness, and tachycardia.
Emergency medicine physicians, poison control specialists, drug policy advocates, harm reduction workers.
~100x higher receptor affinity than cannabis
What the researchers found
From 944 studies screened, 49 met inclusion criteria (2010-2022). Synthetic cannabinoids primarily affected neurological and cardiovascular systems, with common symptoms including seizures, altered consciousness, tachycardia, and hypertension. Hospital and ICU admissions varied reflecting toxicity complexity. Compared to cannabis, SC use was linked to more severe cardiovascular and neurological complications. Rare complications included thromboembolic events and immune thrombocytopenic purpura. Participants were predominantly young adult males (ages 12-72).
Why it matters
Synthetic cannabinoids are often marketed as legal alternatives to cannabis, but their 100-fold higher receptor affinity translates to dramatically more dangerous clinical outcomes. This comprehensive review documents the full spectrum of adverse effects, providing evidence for public health campaigns and emergency medicine protocols.
The numbers in context
944 studies screened. 49 included. SC receptor affinity ~100x greater than cannabis. Common effects: seizures, altered consciousness, tachycardia, hypertension. Predominantly young adult males. Ages 12-72. Published 2010-2022.
How the study worked
Systematic review following PRISMA guidelines across PubMed, Embase, and Lilacs databases. 944 studies screened; 49 published 2010-2022 included. Focused on clinical effects associated with SC use, excluding case reports, other reviews, animal studies, and those on psychiatric symptoms or therapeutic uses only.
What this study cannot tell us
Heterogeneous study designs and populations limit direct comparisons. Excluded psychiatric-only outcomes, potentially underestimating total burden. Rapid emergence of new SC compounds means findings may not cover newest variants. Publication bias toward severe cases may overestimate typical toxicity.
How to read the evidence
Strong: systematic review following PRISMA guidelines with large search scope (944 studies) and clear clinical findings across 49 included studies.
When this study was published
2025 study (literature 2010-2022)
The bigger picture
As synthetic cannabinoids evolve rapidly to evade regulation, the clinical consequences documented here underscore the importance of distinguishing between natural cannabis and synthetic alternatives in both public health messaging and emergency care. The severity of SC toxicity argues against treating them as equivalent to cannabis in policy or clinical contexts.
Questions still open
- Are newer synthetic cannabinoid variants more or less toxic than those studied here? Would cannabis legalization reduce SC use? What emergency protocols best manage the unique toxicity profile of SCs?
Common questions
Are synthetic cannabinoids more dangerous than marijuana?
What are the most common side effects of synthetic cannabinoids?
Read the original research
Adverse clinical effects associated with the use of synthetic cannabinoids: A systematic review.
Drug and alcohol dependence, 272, 112698
Citation
Prete, Mariana M; Feitosa, Gabriel T B; Ribeiro, Maria A T; Fidalgo, T M; Sanchez, Zila M. (2025). Adverse clinical effects associated with the use of synthetic cannabinoids: A systematic review.. Drug and alcohol dependence, 272, 112698. https://doi.org/10.1016/j.drugalcdep.2025.112698
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