EM · Toxicology and environmental emergencies

Opioid poisoning and the opioid toxidrome (emergency department diagnosis and management)

Also known as Opioid overdose · Opiate toxicity · Heroin overdose · Naloxone-reversible coma · Fentanyl overdose

Opioid poisoning is the mu-receptor toxidrome of coma, miosis and respiratory depression. Support ventilation first. Intravenous naloxone is preferred because it can be titrated (Williams); clinical reversal doses sit in the 0.4 to 1.2 mg range (Melichar). Out of hospital, 2 mg intranasal or intramuscular reversed suspected heroin overdose with similar 10-minute response rates (Kerr). A naloxone infusion of two-thirds of the effective bolus per hour maintains levels after reversal (Goldfrank). After naloxone for heroin, one hour of observation can be enough if the patient mobilises as usual, has normal vital signs and GCS 15 (Willman). Long-acting methadone (mean elimination half-life 59 hours in a switch cohort) needs an infusion, not a single bolus and discharge. Tramadol overdose is dominated by seizures; Hunter serotonin toxicity from tramadol alone is uncommon.

Checked against its sources on 4 Sept 2026