Cannabis Overdose: Recognition and Treatment

Mechanism

Clinical Features of Overdose

Mild to Moderate

• Euphoria, relaxation, altered time perception
• Conjunctival injection (red eyes)
• Tachycardia
• Impaired motor coordination, muscle weakness
• Heightened sensory perception

High-Dose / Severe

• Anxiety and acute panic reactions
• Paranoia and delusions
• Disorientation and delirium
• Acute psychosis (especially in susceptible individuals)
• Nausea and vomiting (can be cyclic - see Cannabinoid Hyperemesis Syndrome below)
• Rarely: seizures (especially in children ingesting edibles)

Rare / Severe Complications

• IV injection of boiled cannabis concentrate can cause: acute renal failure, hepatitis, gastroenteritis, anemia, and thrombocytopenia
• Lactic acidosis (reported with cannabinoid gummies, PMID 39600759)
• Status epilepticus in pediatric edible ingestions (PMID 41050035)

Emergency Management

1. Immediate Stabilization

• Place the patient in a quiet, low-stimulation room (reduces panic and agitation)
• Cardiovascular and neurologic monitoring
• IV access; monitor vital signs
• Reassure the patient in a calm, non-judgmental manner - therapeutic reassurance ("talking down") is highly effective for anxiety/panic

2. Symptomatic Pharmacotherapy

3. Gastrointestinal Decontamination

• Generally not indicated in adults
• May be considered in children under 16 with large oral ingestion within 2 hours of presentation (activated charcoal or gastric lavage in selected cases)

4. Hydration

• IV fluids for dehydrated patients or those with persistent vomiting

Cannabinoid Hyperemesis Syndrome (CHS)

• Standard antiemetics (metoclopramide, ondansetron) often fail
• Benzodiazepines or antipsychotics (haloperidol, droperidol) are more effective
• Topical capsaicin cream applied to the abdomen - shown to reduce vomiting episodes in the ED setting (Wagner et al., Clin Toxicol 2020)
• Hot showers (patient's typical self-remedy) - compulsive bathing is a hallmark of CHS
• Definitive treatment: cessation of cannabis use

Special Populations

Children / Toddlers

• Accidental ingestion of edibles is increasingly common as legalization expands
• Children are disproportionately vulnerable: deeper CNS depression, higher risk of seizure, respiratory depression, and prolonged sedation
• A 2026 case series (PMID 41611557) highlights accidental ingestions in toddlers causing significant toxicity requiring monitoring
• Gastric decontamination is more likely to be appropriate in pediatric cases

Pregnant Patients

• Avoid benzodiazepines if possible; use lowest effective dose if necessary
• Neonatal CNS effects possible

Disposition

• Most adults with mild-moderate intoxication can be observed 4-6 hours and discharged once symptoms resolve
• Admit if: persistent psychosis, hemodynamic instability, seizures, very young children, or significant co-ingestion
• All patients should receive brief substance use counseling
• Patients with underlying psychiatric illness warrant psychiatric evaluation
• Chronic heavy users or those with CUD: refer to behavioral therapy (CBT, motivational enhancement therapy) - these are first-line as no FDA-approved pharmacotherapy exists for cannabis use disorder

Key Points Summary

1. Supportive care is the cornerstone - no antidote exists
2. Quiet environment + reassurance are often sufficient for mild cases
3. Benzodiazepines are the workhorse drug for agitation, anxiety, psychosis, and seizures
4. CHS requires capsaicin, antipsychotics/benzodiazepines, and cannabis cessation
5. Edible ingestions (especially in children) can produce delayed, prolonged, and severe toxicity due to slow GI absorption
6. Rule out co-ingestion of other substances, which significantly changes management