Synthetic cannabinoids
Drugs of abuse
Drugs of abuse
Lab-made CB1 agonists sprayed on plant material or put in vape liquids («K2», «Spice»). Far stronger than THC and missed by routine urine tests.
Also called: K2, Spice, MDMB-FUBINACA and related indazole compounds
Quick facts
- Group
- Drugs of abuse
- Target
- Cannabinoid receptor 1 (CB1)
- Used for
- No medical use for the illicit products
- Key effects
- Agitation · Tachycardia and raised blood pressure
- Monitor
- Heart rate · Seizures and level of consciousness
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows the synthetic cannabinoid MDMB-FUBINACA bound to the human CB1 receptor in complex with its G protein.
Synthetic cannabinoids are a large, changing family of chemicals made to activate CB1, the same receptor as THC. Unlike THC, which is a partial agonist, most are high-efficacy (full) agonists, so the CB1 response is much stronger. Their effects on other receptors are largely unknown, and illicit batches vary and may be contaminated, which makes the clinical picture unpredictable.
- Product sprayed on herbs or in vape liquid is smoked or vaped
- The compound fully activates CB1 receptors
- Much stronger effect than THC, plus unknown off-target actions
- Agitation, psychosis, seizures, tachycardia
Indications
- No medical use for the illicit products; some synthetic cannabinoids are licensed medicines (for example dronabinol)
- Clinical relevance: severe cannabinoid intoxication with agitation, psychosis or seizures Cannabis toxicity and cannabinoid hyperemesis syndrome →
Adverse effects
Common
- Agitation, anxiety, paranoia and panic
- Tachycardia and raised blood pressure
- Nausea and vomiting
- Numbness, tingling and tremor
Contraindications
- No medical use for illicit products: there is no safe dose
- Especially dangerous with heart disease, epilepsy or psychotic illness
Key interactions
- Alcohol and other CNS depressants
- Additive sedation and impairment
- Stimulants and energy drinks
- More tachycardia, hypertension and seizure risk
What is monitored
- Heart rate, blood pressure, temperature and ECG
- Seizures and level of consciousness
- Creatinine, electrolytes and creatine kinase
- Mental state and psychosis
Pregnancy and breastfeeding
No safety data; their strong CB1 activity and unknown contaminants make any use in pregnancy hazardous.
Nursing care
- Remember that a negative cannabis urine screen does not rule them out
- Keep the patient in a calm space; benzodiazepines are used for agitation and seizures
- Monitor urine output and kidney function
- Offer referral for substance use support
Pharmacokinetics
- Absorption
- Smoked on dried plant material or vaped from liquid cartridges
- Metabolism
- Varies with the compound; most are not detected by standard cannabis immunoassays
Test yourself
Think of the answer, then tap the question to see it.
How does the action of synthetic cannabinoids at CB1 differ from THC?
Most are high-efficacy (full) agonists, while THC is a partial agonist, so their effects are much stronger.
Why can a urine drug screen be negative in synthetic cannabinoid intoxication?
Their structures differ from THC, so routine cannabis immunoassays do not detect them.
What are two serious complications of synthetic cannabinoids?
Any two of: seizures, psychosis, myocardial infarction, acute kidney injury, death.
Connections
← Back to the class: Drugs of abuse
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Synthetic Cannabinoids (National Institute on Drug Abuse (NIDA), 2026); Drugs A to Z (National Institute on Drug Abuse (NIDA), 2025); Guía para el Manejo de Emergencias Toxicológicas (Ministerio de Salud y Protección Social; Organización Panamericana de la Salud, 2017).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.