ALiEM ACMT Toxicology Visual Pearl: Cookie Monster

4. Tetrahydrocannabinol (THC)

Background

“Edibles” can take many forms, such as cookies, candies, and drinks, and commonly contain delta-9-tetrahydrocannabinol (THC). THC can cause somnolence and vomiting, particularly in pediatric patients [1,2]. With increased legalization, leading to increased usage and availability, there has been an increase in unintentional exposures with more ED visits and hospitalizations over the last decade [1,3].

What is THC, and how does it work? [2, 4-6]

• Cannabis is derived from the Cannabis sativa and Cannabis indica
• The plant contains many different cannabinoids, such as the various forms of THC and cannabidiol (CBD).
• THC is responsible for the psychoactive effects. CBD is non-psychoactive.
• CBD is being studied for potential medicinal uses such as for anxiety, epilepsy, and inflammation.
• THC is a partial agonist at cannabinoid receptors, specifically CB1 and CB2, which are part of the endocannabinoid system. This system affects appetite, memory, pain perception, movement, metabolism, cardiovascular function, and immune response.
• The exact mechanism of psychoactive effects is unknown.

What is the clinical presentation of THC toxicity? [1, 7]

• Symptoms vary depending on the route and amount of THC consumed.
• Symptoms occur faster and are often more significant with ingestion of higher concentrations or doses.
• Symptom onset can occur more quickly after a drink than after a cookie.
• In pediatric patients, symptoms may be prolonged and more severe than in adults.
• Common presentations include:
  • Anxiety
  • Ataxia
  • Conjunctival injection
  • Dry mouth
  • Euphoria
  • Increased appetite
  • Nausea and vomiting
  • Somnolence
  • Tachycardia
• More severe toxicity may present with:
  • Agitation
  • Dysrhythmia
  • Hypotension
  • Lethargy and coma
  • Myoclonus/seizures
  • Respiratory depression

Why do symptoms tend to be more severe in children? [1,5,7-11]

• Edible THC products are mistaken for food or candy, particularly when packaged similarly, and children unintentionally consume large amounts.
• Children have a smaller body mass and receive a higher dose of THC per kilogram.
• Symptoms can be delayed when ingested and thus unrecognized.
• Children may be unable to communicate early symptoms, leading to delays in recognition.

How can you diagnose THC toxicity? [6,12,13]

• Diagnosis is based primarily on clinical history and presentation. It is important to inquire about THC-containing products in the home.
• Urine drug screen (UDS) for THC/cannabinoids may aid in unclear cases
  • Confirmatory testing for a positive THC on UDS can be done with Gas Chromatography/Mass Spectrometry (GC/MS).

What is the treatment for THC toxicity? [6,7,14]

Treatment is typically supportive care and includes:

• Benzodiazepines for seizures or agitation
• IV fluids for dehydration
• Significant toxicity may require admission and potentially respiratory support and ICU level of care.
• Clinicians may contact Poison Control at 1-800-222-1222

Bedside Pearls

• THC ingestion via edibles is becoming increasingly common.
• Common clinical presentations include somnolence, ataxia, and vomiting.
• More severe symptoms can include seizures and dysrhythmia.
• Pediatric patients are at higher risk for more severe toxicity due to unintentional ingestions of edibles labeled as cookies or candies and higher mg/kg ingestions due to their smaller body size.
• Most cases resolve with supportive care, but severe symptoms may require ICU-level monitoring.