Hallucinogen toxicity encompasses a spectrum of adverse effects from classic serotonergic psychedelics (LSD, psilocybin, DMT, mescaline), phenethylamine derivatives (MDMA, 2C series, NBOMe compounds), and dissociative hallucinogens (PCP, ketamine). Most presentations involve mild-to-moderate effects managed with supportive care, but life-threatening complications including hyperthermia, seizures, rhabdomyolysis, serotonin syndrome, and cardiac arrest can occur, particularly with synthetic compounds like NBOMes and MDMA. [1-3]
1. History
- Identify the specific substance ingested (LSD, mushrooms, MDMA, "acid," "molly," "N-bomb"), route (oral, sublingual, insufflation, IV), dose, and timing [3]
- Ask about co-ingestions — 41% of psychedelic exposures involve concomitant substances [2]
- Characterize perceptual changes: visual hallucinations, synesthesias, depersonalization, derealization [3]
- Assess for behavioral/psychological changes: anxiety, paranoia, fear of "losing one's mind," impaired judgment [3]
- Determine setting of use (rave/dance club, home, outdoor) — environmental heat and exertion increase risk of MDMA-related hyperthermia [4]
- Prior psychiatric history, especially psychotic disorders, bipolar disorder, or HPPD
- Current medications, particularly SSRIs, SNRIs, MAOIs, and lithium — risk of serotonin toxicity [5]
2. Alarm Features
- Hyperthermia (core temp >40°C / 104°F) — rapidly life-threatening, especially with MDMA [4][6]
- Seizures — more common with NBOMe compounds (8.8% of exposures) and MDMA [7-8]
- Severe agitation/excited delirium with violent behavior — risk of rhabdomyolysis and sudden death [9-10]
- Clonus, rigidity, and hyperreflexia — suggests serotonin syndrome [11-12]
- Coma or obtundation — especially with polysubstance use [3]
- Chest pain, dysrhythmias — particularly with hallucinogenic amphetamines and NBOMes [13-14]
- Metabolic acidosis, oliguria — suggests rhabdomyolysis or multiorgan failure [7]
- Suicidal ideation or self-harm behavior during or after intoxication [3][15]
3. Medications
First-line treatment
- Benzodiazepines are the cornerstone of management — lorazepam 2–4 mg IV/IM or midazolam 5 mg IM for agitation, anxiety, and seizures [10][16-17]
- Benzodiazepines also control psychomotor agitation that produces heat and rhabdomyolysis [6]
Second-line/adjunctive
- Cyproheptadine (4–8 mg PO) if serotonin syndrome is suspected — serotonin antagonist; only available PO [11-12]
- External/immersive cooling for hyperthermia — evaporative or ice water immersion preferred over cooling blankets [6]
Contraindicated/caution
- Antipsychotics should generally be avoided in hallucinogen toxicity — risk of lowering seizure threshold, NMS, hypotension, and worsening hyperthermia [4]
- Avoid physical restraints without adequate sedation — associated with death in severe agitation [10]
- Dantrolene for MDMA-induced hyperthermia has conflicting evidence [6]
- Urine acidification is contraindicated if CK is elevated (promotes renal myoglobin precipitation) [4]
4. Diet
- Aggressive IV fluid resuscitation is critical for rhabdomyolysis prevention and treatment, and for thermoregulation in hyperthermia [4]
- MDMA can cause hyponatremia from both SIADH and excessive water intake — avoid free water overload; use isotonic fluids [3]
- NPO if altered mental status or risk of aspiration
- No specific dietary triggers; however, MDMA toxicity is worsened by dehydration and exertion in hot environments
5. Review of Systems
- Neuropsychiatric: hallucinations (visual > auditory), paranoia, anxiety, panic, depersonalization, confusion, agitation, suicidal ideation [1][3]
- Cardiovascular: palpitations, chest pain, dyspnea [2][13]
- GI: nausea, vomiting (especially psilocybin) [18]
- Musculoskeletal: muscle rigidity, myalgias (rhabdomyolysis) [9]
- Genitourinary: decreased urine output (AKI from rhabdomyolysis)
- Constitutional: diaphoresis, chills, headache [18]
- Neurologic: seizures, tremor, incoordination, blurred vision [3]
6. Collateral History and Family History
- Collateral from friends/bystanders is often the most valuable source — identify substance, dose, timing, route, and co-ingestions
- Ask about the source of the substance — "LSD" sold on blotter paper may actually be NBOMe, which has a significantly higher toxicity profile [7][19]
- Family history of psychotic disorders or bipolar disorder — increases risk of substance-induced psychosis and prolonged psychiatric complications [20]
- Social context: rave/festival setting, prior substance use history, access to novel psychoactive substances
7. Risk Factors
- Polysubstance use — present in 41% of psychedelic exposures reported to poison centers [2]
- Synthetic hallucinogens (NBOMes, 2C series) carry significantly higher morbidity and mortality than classic psychedelics; NBOMe death rate ~2.3% in poison center data [7-8]
- MDMA in hot, crowded environments with exertion — highest risk for fatal hyperthermia [4]
- Concurrent serotonergic medications (SSRIs, MAOIs) — risk of serotonin syndrome, especially with MDMA and ayahuasca (contains MAOIs) [5][21]
- Preexisting neuropsychiatric disorders — serious adverse events in ~4% of this population vs. none in healthy individuals [20][22]
- Age 13–29 years and male sex predominate (74–78% male) [1]
- Unknown substance identity — users may not know what they actually ingested
8. Differential Diagnosis
- Sympathomimetic toxidrome (amphetamines, cocaine) — similar tachycardia, hypertension, agitation, mydriasis; distinguished by prominent hallucinations and perceptual distortions in hallucinogen toxicity [3][23]
- Serotonin syndrome — clonus, hyperreflexia, and diaphoresis distinguish it; can co-occur with hallucinogen use, especially MDMA + serotonergic drugs [5][12]
- Anticholinergic toxidrome — dry skin, urinary retention, decreased bowel sounds, and normal reflexes distinguish it from hallucinogen/serotonergic toxicity [12]
- Neuroleptic malignant syndrome — slow onset (days), lead-pipe rigidity, bradykinesia, hyporeflexia [12]
- Primary psychotic disorder (schizophrenia, mania) — no temporal relationship to substance use; may be unmasked by hallucinogens [3]
- Hypoglycemia, CNS infection, seizure disorder, intracranial pathology — must be excluded in undifferentiated altered mental status [3]
- PCP intoxication — nystagmus (horizontal, vertical, or rotatory) and bizarre violent behavior help distinguish from other hallucinogens [3]
9. Past Medical History
- Psychiatric history — psychotic disorders, bipolar disorder, PTSD, depression (risk of exacerbation or substance-induced psychosis) [20][22]
- Prior episodes of hallucinogen use or HPPD [20][24]
- Cardiac history — underlying arrhythmias, structural heart disease (increased risk with sympathomimetic effects) [13]
- Seizure disorder — lowered threshold with many hallucinogens
- Renal or hepatic disease — impaired drug metabolism and increased vulnerability to organ injury [3]
- Current medications — SSRIs, MAOIs, lithium, other serotonergic agents [5]
10. Physical Exam
Vital signs
- Tachycardia (18–39% of cases), hypertension, hyperthermia [1][25]
- Tachypnea
Key findings
- Mydriasis (pupillary dilation) — hallmark finding [3][25]
- Diaphoresis (distinguishes from anticholinergic toxidrome where skin is dry) [12]
- Hyperreflexia, clonus (especially lower extremities) — suggests serotonin toxicity [12]
- Nystagmus — more prominent with PCP; can occur with other hallucinogens [3]
- Tremor, incoordination, ataxia [3]
- Agitation, restlessness, combativeness [1]
- Muscle rigidity — in severe serotonin syndrome or NMS [12]
Focused exam maneuvers
- Rectal/core temperature (not oral/axillary — unreliable in agitated patients)
- Deep tendon reflexes and clonus assessment (ankle clonus most sensitive for serotonin syndrome) [12]
- Skin assessment: diaphoresis vs. dry skin (serotonergic vs. anticholinergic)
- Bowel sounds: hyperactive (serotonergic) vs. absent (anticholinergic) [12]
- Trauma survey — falls, self-injury from impaired judgment [3]
11. Lab Studies
- Point-of-care glucose — rule out hypoglycemia in altered mental status [17]
- Comprehensive metabolic panel — electrolytes (hyponatremia with MDMA), renal function (AKI), hepatic function [3]
- Creatine kinase (CK) — rhabdomyolysis screening; elevated CK reported in 100% of confirmed 25I-NBOMe cases in one series [26]
- Lactate — metabolic acidosis assessment
- Coagulation studies — DIC screening if severe toxicity [7]
- Urine drug screen — limited utility; classic hallucinogens (LSD, psilocybin) and NBOMes are not detected on standard immunoassay panels; may detect amphetamines (MDMA cross-reacts) or PCP [3][21]
- Serum ethanol, acetaminophen, salicylate — co-ingestion screening
- Urinalysis — myoglobinuria
- VBG/ABG — if concern for metabolic acidosis
12. Imaging
- Imaging is generally unnecessary for uncomplicated hallucinogen intoxication
- CT head — indicated if focal neurologic deficits, prolonged altered mental status, head trauma, or concern for intracranial pathology [3]
- Chest X-ray — if respiratory distress, aspiration risk, or concern for pneumothorax (reported with hallucinogen use) [3]
- No gold-standard imaging for hallucinogen toxicity itself
13. Special Tests
- Hunter Serotonin Toxicity Criteria — decision rules for diagnosing serotonin syndrome: spontaneous clonus, inducible clonus + agitation/diaphoresis, ocular clonus + agitation/diaphoresis, tremor + hyperreflexia, or hypertonia + temperature >38°C + ocular/inducible clonus [12]
- Poison Control consultation (800-222-1222) — recommended for all suspected hallucinogen exposures, especially novel psychoactive substances [17]
- Confirmatory toxicology (LC-MS/MS) — can identify specific NBOMes, synthetic tryptamines, and other novel compounds not detected on standard screens; typically send-out testing [26]
- Bedside ultrasound — cardiac function assessment if hemodynamic instability
14. ECG
- Obtain ECG in all symptomatic hallucinogen exposures, especially MDMA, NBOMes, and unknown substances [27]
- QT prolongation — reported with MDMA, NBOMe compounds, and psychotropic co-ingestions; predisposes to torsades de pointes [14][27-28]
- Sinus tachycardia — most common finding [1]
- QRS prolongation — reported with MDMA at high doses [29]
- ST changes — MDMA can cause coronary vasospasm and stress cardiomyopathy [6][13]
- Continuous cardiac monitoring recommended until the patient is free of drug influence and ready for discharge [27]
15. Assessment
Hallucinogen toxicity typically presents as a serotonergic toxidrome with perceptual disturbances (hallucinations, synesthesias), psychological distress (anxiety, paranoia, agitation), and autonomic activation (mydriasis, tachycardia, hypertension, diaphoresis). [1][3]
Severity stratification
- Mild: Anxiety, mild perceptual changes, tachycardia, mydriasis — most common presentation (~60% moderate effect) [1]
- Moderate: Significant agitation, persistent hallucinations, hypertension requiring monitoring
- Severe: Hyperthermia >40°C, seizures, rhabdomyolysis, serotonin syndrome, coma, cardiac arrest — infrequent but can occur, especially with NBOMes and MDMA [2][7]
Classic psychedelics (LSD, psilocybin) have a wide therapeutic index and rarely cause death as single agents. NBOMe compounds and MDMA carry substantially higher risk of severe toxicity and death. [1][7-8]
Complications to consider: Rhabdomyolysis → AKI, DIC, hepatic failure, serotonin syndrome, HPPD (long-term), substance-induced psychosis, self-injury from impaired judgment. [3][9][20]
16. Treatment Plan
Initial stabilization
- ABCs — protect airway if obtunded; RSI with rocuronium preferred if rhabdomyolysis present [17]
- Place in a calm, low-stimulation environment with reassurance ("talk-down")
- Continuous cardiac monitoring and core temperature monitoring
Agitation/anxiety
- Benzodiazepines first-line: lorazepam 2–4 mg IV/IM or midazolam 5–10 mg IM; repeat as needed [6][10][16]
- Avoid physical restraints without concurrent chemical sedation [10]
Hyperthermia (>40°C)
- Aggressive evaporative or ice water immersion cooling [6]
- IV crystalloid resuscitation
- Benzodiazepines to reduce thermogenesis from agitation
- Consider paralysis and intubation if refractory [4]
- Dantrolene — conflicting evidence; may consider if temp >39°C [4][6]
Serotonin syndrome
- Discontinue all serotonergic agents
- Benzodiazepines for agitation
- Cyproheptadine 12 mg PO loading, then 2 mg q2h (only available PO) [11-12]
Seizures
Rhabdomyolysis
- Aggressive IV normal saline resuscitation; target UOP 1–2 mL/kg/hr
- Serial CK and renal function monitoring
Hypertension/coronary vasospasm
- Benzodiazepines first; if refractory, consider nitrates or phentolamine [6]
- Avoid beta-blockers (risk of unopposed alpha stimulation with sympathomimetic hallucinogens)
17. Disposition
Discharge criteria
- Symptom resolution, normal vital signs, ambulatory, tolerating PO, no suicidal ideation
- Most LSD and psilocybin patients are treated and released from the ED [1]
- Observation period of 4–6 hours for psilocybin, 8–12+ hours for LSD (longer half-life) [3][25]
Admission criteria
- Persistent hyperthermia, seizures, rhabdomyolysis (elevated CK), AKI, metabolic acidosis
- Hemodynamic instability or dysrhythmias
- Persistent altered mental status or psychosis
- LSD patients are more likely to require admission than psilocybin patients [1]
ICU admission
Specialist consultation triggers
- Toxicology/Poison Control — all cases with unknown substance, severe toxicity, or novel psychoactive substances [17]
- Psychiatry — substance-induced psychosis, suicidal ideation, persistent psychiatric symptoms
- Nephrology — AKI from rhabdomyolysis
18. Follow Up / Return Precautions
Follow-up timing
- PCP/psychiatry follow-up within 48–72 hours if discharged with residual psychiatric symptoms
- Substance use counseling referral at discharge
- Recheck renal function and CK in 24–48 hours if rhabdomyolysis was present
Return precautions — instruct patients to return for
- Recurrent hallucinations or perceptual disturbances (may indicate HPPD) [20][24]
- Persistent anxiety, paranoia, depersonalization, or mood instability [30]
- Fever, dark urine, decreased urine output
- Chest pain, palpitations, syncope
- Suicidal thoughts or self-harm urges
Patient counseling
- Educate that "LSD" purchased illicitly may actually be NBOMe, which is far more dangerous [7][19]
- HPPD can develop after even a single use — type 1 (transient flashbacks) or type 2 (chronic, potentially irreversible perceptual disturbances) [20][24]
- Expected recovery: classic psychedelic effects typically resolve within 6–12 hours (LSD) or 4–6 hours (psilocybin); subacute mood changes, sleep disturbance, or "afterglow" effects may persist days to weeks [25][30]
- Avoid serotonergic medications without medical guidance if planning future use
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