- Assess for adequacy of respiration / ventilation.
- Consider finger stick glucose for unclear cases.
- Consider possible cointoxicants.
- In the United States, the American Association of Poison Control Centers at 1-800-222-1222 is available 24 hours a day to connect callers directly to their region's poison center. They are also available online.
Cannabis is the third most used psychoactive substance globally, only exceeded in frequency of use by alcohol and tobacco. In the United States, lifetime prevalence of use is 46%, with 18% of the population 12 years and older reporting use. Males are more likely to use cannabis, as are those aged 18-25 years. Psychosocial factors such depressed mood, anxiety, use of other substances, schizophrenia, and other psychiatric disorders have been correlated with cannabis use in some studies.
While the flower of the cannabis plant contains hundreds of biologically active substances, the psychoactive effects of cannabis are believed to be predominantly mediated by delta-9-tetrahydrocannabinol (THC). This acts as a partial agonist of central and peripheral cannabinoid receptors, but the precise mechanism by which this produces its psychoactive effects is not entirely understood.
Cannabis intoxication produces both psychologic and physiologic effects. Psychologic effects vary greatly between users; the most common self-reported effects are relaxation, euphoria, increased appetite, altered perceptions of the senses, and an altered perception of time. Physiologic effects include dose-dependent increases in heart rate and blood pressure, conjunctival injection, xerostomia, orthostatic hypotension, decreased coordination, and decreased psychomotor activity.
When cannabis smoke is inhaled, the peak effect lasts around 15-30 minutes but can last up to 4 hours. When cannabis is ingested parenterally, the peak effect lasts from 30 minutes to 3 hours but can last up to 12 hours.
The legal status of cannabis for medicinal and recreational use varies among US states. In states where cannabis is legal recreationally, there has been an increased incidence of nonintentional pediatric exposures. The National Academy of Medicine reviewed the evidence supporting the medical use of marijuana and reported that it shows promise as therapy for some conditions, but further research is needed. Synthetic THC (dronabinol) has US Food and Drug Administration (FDA) approval for the control of chemotherapy-related nausea and vomiting, breakthrough postoperative nausea and vomiting, and for appetite stimulation in HIV-infected patients with anorexia-cachexia syndrome.
While the large medial lethal dose (LD50) of cannabis typically precludes significant toxicity in adults, several case reports and case series have documented clinically significant events in pediatric overdose. The most common symptoms include lethargy, tachycardia, mydriasis, ataxia, and hypotonia, which may progress to respiratory depression and loss of airway integrity with aspiration as a consequence. In a recent case series, nearly 20% of patients required admission to the pediatric intensive care unit for observation, while 6% required intubation for respiratory support. Because the differential diagnosis for altered mental status in children is broad, children presenting with cannabis toxicity may be subject to invasive diagnostic testing, neuroimaging, and antibiotic therapy for presumed meningitis. As in the adult patient, care is primarily supportive. See pediatric edible cannabis toxicity for more information.
Related topic: synthetic cannabinoid poisoning