General MedicineTier 1Disease (DEADMAN)

Psychiatry - overdose or toxic effects of illicit drug use

Description

Overdose/toxicity from illicit substances - opioids (heroin, illicit fentanyl/nitazenes), stimulants (methamphetamine, cocaine, MDMA), sedatives (GHB, benzodiazepines obtained illicitly), cannabis, novel psychoactive substances
Illicit fentanyl/nitazene contamination of the heroin/counterfeit pill supply has raised overdose potency unpredictability

Epidemiology

Opioid-related deaths rising in Australia, driven by pharmaceutical opioids and increasing illicit fentanyl detection
Methamphetamine-related presentations (agitation, psychosis, cardiovascular events) remain a major ED burden
Polysubstance use (esp. combined opioid + benzodiazepine or alcohol) substantially raises fatality risk

Aetiopathogenesis

Opioid toxicity: mu-receptor mediated respiratory depression -> hypoxia -> death
Stimulant toxicity: catecholamine excess -> hypertension, tachyarrhythmia, hyperthermia, seizures, intracranial haemorrhage
GHB: rapid-onset CNS/respiratory depression, narrow therapeutic window, characteristic rapid recovery
MDMA: serotonergic + sympathomimetic + SIADH (hyponatraemia, esp. with excess water intake) + hyperthermia

Diagnosis

Toxidrome recognition (see pharm-tox toxidrome/coma notes) - pupils, vital signs, mental state, skin findings
Collateral history from bystanders re: substance(s) used, quantity, co-ingestants
Urine/serum tox screen supportive only - does not reliably detect novel synthetic opioids (fentanyl analogues, nitazenes) on standard immunoassay

Management

1. Opioid toxidrome

Naloxone IM/IN titrated to adequate ventilation, repeat dosing likely needed for potent/long-acting agents
Observe for re-narcotisation (naloxone half-life shorter than many opioids) - extended observation for high-potency/long-acting exposures
Provide take-home naloxone on discharge to the patient and their contacts - free, no prescription needed

2. Stimulant toxicity

Benzodiazepines first-line for agitation/hypertension/tachycardia (avoid beta-blockers alone - unopposed alpha stimulation risk)
Active cooling for hyperthermia, IV fluids, treat seizures per standard protocol

3. GHB toxicity

Supportive - airway protection, typically rapid spontaneous recovery within hours; avoid unnecessary intubation if transient

4. MDMA toxicity

Cooling, benzodiazepines, cautious fluid replacement (hyponatraemia risk with SIADH - avoid excess hypotonic fluids); hypertonic saline if severe symptomatic hyponatraemia

5. All presentations

Brief intervention/harm reduction advice, referral to drug and alcohol services, discuss safer use practices and overdose risk after abstinence periods

Associations

Blood-borne virus exposure with injecting use
Co-occurring mental illness, housing instability, criminal justice involvement
Polysubstance-related unpredictable overdose presentations

Natural history & complications

Most acute toxicity resolves with supportive care and specific antidotes where available
Overdose risk spikes after any period of abstinence (reduced tolerance) - detox, incarceration, hospitalisation
Repeated non-fatal overdose is a strong predictor of eventual fatal overdose - each presentation is an opportunity for harm-reduction intervention

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