With the increased legalization, decriminalization and utilization of cannabis, EMS providers can expect to see increased overdoses, pediatric ingestion and negative side effects.

In recent years, there has been a significant rise in the number of states that allow for legal cannabis use. As of 2022, 37 states allow for medical cannabis use with a doctor’s prescription while 18 states allow for recreational cannabis use.1 Advancements in medicine have identified many safe and therapeutic indications for cannabis. However, with the ever growing body of legalized use, EMS providers will likely encounter more cannabis-related incidents than ever before. For this reason, it is imperative that EMS providers understand the pharmacology, pathophysiology and medicolegal considerations related to cannabis use.


Cannabis, often referred to as marijuana, is comprised of four different species of plant. Of these, Cannabis sativa is the most commonly used plant in western society. Each cannabis plant contains multiple phenotypes with different chemical compositions. In fact, each cannabis plant can contain over 500 different phytocannabinoids – an individual chemical substance in each plant.

The two main (most studied) compounds found in cannabis include THC (trans-delta-9-tetrahydrocannabinol) and CBD (cannabidiol). THC is the primary psychoactive compound found in cannabis and is responsible for central nervous system intoxication.2 THC interacts with receptors in the brain, spinal cord and peripheral nerves. One particular group of target receptors for THC are abundantly present in the cerebellum, basal ganglia, cerebral cortex and the hippocampus.2 These target sites explain why THC causes many of the effects commonly observed when someone is “high”- ataxia, inhibition and analgesia.2

CBD, the other main component in cannabis, is not psychoactive in the same way as THC.2 CBD provides some level of relaxation and analgesia while preserving gait and mental status. While largely considered to be “safer” than THC, there is some evidence that CBD may modulate the psychoactive effects observed with THC.

Clinical Presentation and Associated Pathology

Patients presenting with acute cannabis intoxication may display any of the following signs and symptoms:

  • Conjunctival injection (red, “bloodshot” eyes)
  • Mydriasis (pupil dilation)
  • Slurred speech
  • Tachycardia, tachypnea, and hypertension
  • Paranoia or confusion
  • Delayed reaction time

The timing and severity of symptoms are largely dependent on route of exposure. For example, inhalation exposure can lead to rapid onset of sign/symptoms due to quick absorption in the lungs.3,4 While variation exists with depth and timing of inhalation, peak levels can often be detected in ten minutes following one inhalation.3 Ingested cannabis, unlike inhaled cannabis, can take hours to demonstrate effects as it will need to traverse the gastrointestinal system to be absorbed into the blood.3,4 The delay in uptake can actually promote overuse of cannabis products, as some individuals may attempt to consume more product when they don’t quickly feel the effects. After a number of hours, the ingested cannabis will take effect and can produce greater effects than the individual originally desired.

These effects may be exacerbated if the patient ingested alcohol before cannabis and may delay the effects of alcoholic intoxication when cannabis is ingested before alcohol.5,6 When used in combination, research further indicates an increased dependence on both substances, decreased cognitive function, and an increased risk of motor vehicle collision.7

In patients with preexisting respiratory conditions, always consider the effect of airway irritants causing wheezing or asthma exacerbation. Also consider the effects of tachycardia, tachypnea, and hypertension in any patient at high risk for myocardial ischemia, such as those with preexisting structural heart damage.

EMS providers must also be aware of cannabis hyperemesis syndrome (CHS), a subset of cyclical vomiting syndrome.8,9 CHS is a disorder characterized by bouts of nausea and vomiting associated most commonly with long-term cannabis use.8,9 While cannabis typically reduces GI inflammation and improves motility, some patients can experience severe GI upset and vomiting as a result of long-term cannabis use. Interestingly, CHS can occur even in the absence of acute use. While the pathophysiology is still unclear, there seems to be a disruption of the “gut-brain” axis that influences the GI system to function appropriately.8,9

The treatment goals for CHS include antiemetics, pain control and electrolyte correction.8,9 While ondansetron is often the treatment of choice for nausea in EMS settings, CHS patients often need antidopaminergic therapy such as haloperidol to receive adequate symptom control.9 Interestingly, patients may report that they feel better with a hot shower, likely due to an underlying hypothalamic influence in the pathological origin of the disease.9 Capsaicin cream, often used to treat arthritis, also seems to be an effective treatment for CHS.9 While these two interventions may not be approved or appropriate for the prehospital care environment, EMS providers may consider the use of warming packs to the abdominal area.

Of note, the signs and symptoms mentioned in this section refer to pure cannabis ingestion. The symptomology may differ with adulterated cannabis products, such as those mixed with other drugs. The symptomology may also differ for synthetic cannabis products such as “K2” or “spice.”

Pediatric Ingestion

Pediatric ingestion of cannabis can be extremely harmful, especially when consumed in large amounts. Neurotoxicity and CNS depression of the pediatric patient can be severe enough to warrant hospitalization and/or intubation. Particularly noteworthy in pediatric patients is the source of cannabis exposure; many pediatric patients are exposed to cannabis products from family members.

In a 2019 study by Nobel et al., researchers examined calls to two state poison control centers reporting cannabis exposure.10 Of 253 included cases, edible ingestion was found to be the most common route of exposure for all age groups.10 Notably, 73.2% of children (n=52) were exposed from edible products that belonged to a family member/caretaker.10 Five pediatric patients even required ICU admission, with one nine-month old and one one-year-old requiring intubation.10

EMS providers need to heed these statistics when encountering any pediatric patient. Cannabis intoxication should be included any time a pediatric patient is encountered who presents with CNS/ respiratory depression, altered mental status, tachycardia, tachypnea, hypertension or ataxia. Furthermore, EMS providers should understand that many children will consume “edibles,” or food mixed with concentrated TCH.11 Edible THC products may come in many forms that look like typical food products:candy, brownies and chocolate.11

As discussed in earlier sections, patients who ingest cannabis may have a delayed presentation. EMS providers should take a full history, including last oral intake and the presence/absence of cannabis in the household to determine possible exposure in pediatric patients.

Medicolegal Considerations for EMS

With the increased use of legal cannabis, the importance of proper and thorough prehospital care reports cannot be overstated. As cannabis use has become more permissive in Canada, Washington State, California and Colorado, the rate of drug impaired driving has equally increased.12 Due to this increase, EMS providers can expect to have their documentation subpoenaed in criminal, civil, and administrative proceedings. What is more, because the THC level of marijuana is highest within the first two hours of ingestion, paramedics and EMTs who are authorized to conduct blood draws can expect greater calls to assist law enforcement after a motor vehicle collision.12 The research on the effect of cannabis on crime rates, occupational related injury, and related socioeconomic issues otherwise remains unclear but nonetheless should be considered by EMS providers whenever responding to a call for service.

To ensure that a cannabis-related call is adequately addressed and documented, EMS providers should observe the patient for any significant findings such as bloodshot eyes, dilated pupils, tachycardia, tachypnea, hypertension, odor consistent with cannabis use, unsteady gait and related signs of potential intoxication.

When speaking with the patient and bystanders who have useful information about the patient’s condition, the EMS provider should avoid pre-judging a patient’s use but rather treat it as any other medication, whether prescribed, over the counter, or herbal, and inquire as to it use, dosage (if known), frequency and method of ingestion. The EMS provider equally should document any pertinent symptoms (i.e. paranoia, nausea, insatiability, etc.).

It cannot be overstated that cannabis use not only may be lawful in your area; but also, may be prescribed for use for a therapeutic purpose. In some areas, however, cannabis may be legal only for medicinal purposes, which should be documented accordingly. Lastly, in other areas, cannabis use may still be illegal but decriminalized or made akin to a regulatory/traffic infraction. Due to these state-by-state variations, EMS providers should strive to be aware of the present state of legalization of cannabis in their respective jurisdictions and adjust their patient assessment approaches accordingly.

EMS providers also must be vigilant in both responding and documenting potential pediatric ingestion of cannabis related products. With legalization, poison control centers have seen an increased number of calls regarding both adolescents and pre-teen ingestion, particularly among cannabis edibles.13 This increase of calls may be attributable to a lack of regulation of cannabis edibles, resulting in unexpected levels of THC products being ingested by the consumer. While states have attempted to reduce rates of overdose with packaging regulations, these regulations have done little to abate the issue. Accordingly, EMS providers should expect their documentation to be reviewed in child abuse and neglect proceedings in addition to traditional criminal and civil proceedings.

EMS agencies should consult with legal counsel about whether mandatory reporting applies when a parent and/or legal guardian fails to safeguard a cannabis related edible from accidental ingestion.

The age of the patient and way in which the cannabis related product was found relates to both the patient’s medical care as well as potential abuse/neglect. Consequently, to properly document such a pediatric-related case, EMS providers should observe and write in sufficient detail the way the cannabis related product was found, the nature of the product, and how it was ingested. For instance, a Nerds or Starburst package with the word “medicated” on it likely has the concentration of cannabis somewhere on the label, which would be relevant for care. However, a self-prepared brownie is unlikely to have such a label. EMS providers also should not hesitate to interview the parents and/or guardian about how their child might have ingested the intoxicant and treat the patient accordingly. The parent and/or guardian’s demeanor, affect, and mode of speech should be documented in addition to the substance of their statement, word-for-word, if possible.

These observations, of course, are in addition to the medically appropriate assessment and treatment for cannabis-related intoxication. It should be documented appropriately as outlined above.


EMS providers should be aware of the different considerations when evaluating a patient with possible cannabis exposure. Cannabis, while effective in a variety of medical scenarios, can pose serious risks to vulnerable populations. EMS providers should always be aware of the CNS, respiratory, and GI effects of cannabis and prepared to treat each effectively. EMS providers should also be aware of the prevalence of accidental ingestion, especially in pediatric populations. Obtaining a full history, including oral intake, is vital to proper treatment of cannabis exposure. As cannabis legalization continues to expand across the U.S., EMS providers should continue educating themselves to respond effectively to these patients when needed.


  1. Yakowicz W. Where is cannabis legal? A guide to all 50 states . Forbes. Forbes Magazine; 2022 . Available from: https://www.forbes.com/sites/willyakowicz/2022/01/10/where-is-cannabis-legal-a-guide-to-all-50-states/?sh=156ca907d19b.
  2. Ebbert JO, Scharf EL, Hurt RT. Medical Cannabis. Mayo Clin Proc. 2018 Dec;93(12):1842-1847. doi: 10.1016/j.mayocp.2018.09.005. PMID: 30522595.
  3. Foster BC, Abramovici H, Harris CS. Cannabis and Cannabinoids: Kinetics and Interactions. Am J Med. 2019 Nov;132(11):1266-1270. doi: 10.1016/j.amjmed.2019.05.017. Epub 2019 May 30. PMID: 31152723.
  4. Ashton CH. Pharmacology and effects of cannabis: a brief review. Br J Psychiatry. 2001 Feb;178:101-6. doi: 10.1192/bjp.178.2.101. PMID: 11157422.
  5. Hartman RL, Brown TL, Milavetz G, Spurgin A, Gorelick DA, Gaffney G, Huestis MA. Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol. Clin Chem. 2015 Jun;61(6):850-69. doi: 10.1373/clinchem.2015.238287. Epub 2015 May 27. PMID: 26019183.
  6. Lukas SE, Benedikt R, Mendelson JH, Kouri E, Sholar M, Amass L. Marihuana attenuates the rise in plasma ethanol levels in human subjects. Neuropsychopharmacology. 1992 Aug;7(1):77-81. PMID: 1326277.
  7. Yurasek AM, Aston ER, Metrik J. Co-use of Alcohol and Cannabis: A Review. Curr Addict Rep. 2017 Jun;4(2):184-193. doi: 10.1007/s40429-017-0149-8. Epub 2017 Apr 27. PMID: 32670740; PMCID: PMC7363401.
  8. Perisetti A, Gajendran M, Dasari CS, Bansal P, Aziz M, Inamdar S, Tharian B, Goyal H. Cannabis hyperemesis syndrome: an update on the pathophysiology and management. Ann Gastroenterol. 2020 Nov-Dec;33(6):571-578. doi: 10.20524/aog.2020.0528. Epub 2020 Sep 16. PMID: 33162734; PMCID: PMC7599351.
  9. Richards JR. Cannabinoid Hyperemesis Syndrome: Pathophysiology and Treatment in the Emergency Department. J Emerg Med. 2018 Mar;54(3):354-363. doi: 10.1016/j.jemermed.2017.12.010. Epub 2018 Jan 5. PMID: 29310960.
  10. Noble MJ, Hedberg K, Hendrickson RG. Acute cannabis toxicity. Clin Toxicol (Phila). 2019 Aug;57(8):735-742. doi: 10.1080/15563650.2018.1548708. Epub 2019 Jan 24. PMID: 30676820.
  11. Wong KU, Baum CR. Acute Cannabis Toxicity. Pediatr Emerg Care. 2019 Nov;35(11):799-804. doi: 10.1097/PEC.0000000000001970. PMID: 31688799.
  12. Sewell RA, Poling J, Sofuoglu M. The effect of cannabis compared with alcohol on driving. Am J Addict. 2009 May-Jun;18(3):185-93. doi: 10.1080/10550490902786934. PMID: 19340636; PMCID: PMC2722956.
  13. Whitehill JM, Harrington C, Lang CJ, Chary M, Bhutta WA, Burns MM. Incidence of Pediatric Cannabis Exposure Among Children and Teenagers Aged 0 to 19 Years Before and After Medical Marijuana Legalization in Massachusetts. JAMA Netw Open. 2019 Aug 2;2(8):e199456. doi: 10.1001/jamanetworkopen.2019.9456. PMID: 31418807; PMCID: PMC6704738.