What is the medical management for a patient presenting with cannabis toxicity, potentially with pre-existing psychiatric conditions such as schizophrenia?

Medical Management of Cannabis Toxicity

For acute cannabis toxicity, provide supportive care with benzodiazepines for agitation and anxiety, haloperidol (2-5 mg IM/PO) for severe psychotic symptoms or refractory agitation, and avoid opioids entirely. 1

Immediate Assessment and Risk Stratification

Rule out life-threatening conditions first before attributing symptoms solely to cannabis toxicity, including acute abdomen, bowel obstruction, mesenteric ischemia, pancreatitis, and myocardial infarction. 2, 3

Age-Specific Presentations to Anticipate:

• Patients <20 years: More likely to present with vomiting (35%), reduced consciousness (22%), and headache (11%); less likely to have acute psychosis (5.5%). 4
• Patients >49 years: Higher risk of hypotension (6.5%), sedation, obtundation, and myocardial ischemia/infarction; lower rates of vomiting (20%), anxiety (14%), and agitation (14%). 5, 4
• Children: Particularly susceptible to seizures and coma, requiring heightened monitoring and additional supportive care. 6

Sex-Specific Considerations:

• Males: More frequently present with hypertension, acute psychosis, chest pain, and seizures. 4
• Females: More commonly experience vomiting, anxiety, and hypotension. 4

Acute Symptom Management Algorithm

For Agitation and Anxiety (Most Common: 23-28% of cases):

• First-line: Benzodiazepines for sedation and anxiolysis, addressing the stress-mediated component of toxicity. 2, 1
• Reserve antipsychotics (haloperidol 2-5 mg IM/PO) only when benzodiazepines are insufficient or frank psychosis is present. 1

For Psychotic Symptoms (9-10% of cases):

• Haloperidol or droperidol for severe cannabis-related psychotic symptoms and refractory agitation. 1
• Have diphenhydramine 25-50 mg PO/IV available for dystonic reactions, or benztropine 1-2 mg IV/IM as alternative. 3

For Nausea and Vomiting (24% of cases):

• If cannabinoid hyperemesis syndrome (CHS) is suspected based on chronic heavy use (>1 year, >4 times weekly), stereotypical episodic vomiting (≥3 episodes annually), and hot water bathing behavior: 2, 3
  • Haloperidol 5 mg IV is most effective, reducing hospital length of stay by nearly 50% (6.7 vs 13.9 hours). 2, 3
  • Add lorazepam 2 mg IV for enhanced symptom control and anxiolysis. 3
  • Apply topical capsaicin 0.1% to the abdomen for TRPV1 receptor activation. 2, 3
  • Alternative options: promethazine 12.5-25 mg IV (central line only), olanzapine 5-10 mg PO daily, or ondansetron 16 mg IV (less effective than haloperidol for CHS). 3
• Avoid opioids as they worsen nausea and carry high addiction risk in this population. 2, 1, 3

For Cardiovascular Symptoms:

• Monitor for beta-adrenergic-mediated tachycardia (14% of cases) and potential myocardial ischemia in at-risk individuals, particularly older adults. 1, 4
• Watch for orthostatic hypotension and bradycardia, especially with heavy acute or chronic use. 1
• Males presenting with chest pain (8% of cases) require cardiac evaluation. 4

For Neurological Symptoms:

• Reduced consciousness (13% of cases, higher in young patients): Provide supportive care and monitor airway protection. 4
• Seizures (2% of cases, more common in children and males): Standard seizure management with benzodiazepines. 6, 4
• Monitor for cognitive impairment and motor skill deterioration that may persist beyond acute intoxication. 1

Critical Contraindications in Psychiatric Populations

Cannabis worsens bipolar disorder with no evidence of therapeutic benefit, increasing risk of manic and psychotic symptom exacerbation, particularly with high-THC doses. 1

For patients with pre-existing schizophrenia or psychotic disorders, cannabis use is associated with increased rates of mental illness and cognitive impairment compared to adults with similar usage patterns. 5

Definitive Management and Counseling

Cannabis cessation is the only definitive treatment and should be strongly recommended. 2, 1, 3

For CHS specifically:

• Complete symptom resolution requires 6+ months of abstinence for definitive confirmation. 2, 3
• Initiate amitriptyline 25 mg at bedtime, titrating weekly to 75-100 mg for prevention. 2, 3

For cannabis withdrawal syndrome (begins after 48 hours of abstinence):

• Supportive care with gabapentin, nabilone, nabiximols, or dronabinol may help manage withdrawal symptoms including irritability, insomnia, headaches, nausea, and stomach pain. 5, 1, 3
• Loperamide for diarrhea and gastrointestinal distress. 3

Common Pitfalls to Avoid

• Do not use opioids for pain or nausea—they worsen symptoms and have high addiction risk. 2, 1, 3
• Avoid polypharmacy without indication, as cannabis has minimal significant drug interactions with most analgesics (NSAIDs, acetaminophen, local anesthetics, ketamine, gabapentinoids). 1
• Do not miss CHS diagnosis—it is frequently underdiagnosed due to limited clinician awareness, leading to extensive unnecessary testing. 2, 3
• Patients may report cannabis helps relieve symptoms, leading to continued use and worsening of the underlying condition. 3
• Synthetic cannabinoids cause unpredictable negative psychological and physiological effects with predominant manifestations of anxiety, agitation, paranoia, hallucinations, tachycardia, nausea, vomiting, and diaphoresis. 7

Special Populations

Pregnant and Breastfeeding Patients:

The FDA and U.S. Surgeon General advise complete avoidance of cannabis in any form, including CBD products, due to negative effects on fetal brain development and increased risk for premature birth. 5

Adolescents:

Heavy or regular cannabis use is associated with impairments in attention, learning, memory, planning, and psychomotor speed, with earlier age of onset exacerbating these adverse effects. 5