FFinalistSouthampton · 2027
Acute care
AKT · Acute care/Toxicology & overdose

Opioid overdose

Opioid receptor agonism → CNS/respiratory depression

Overview

Opioid toxicity causing the classic triad of reduced consciousness, respiratory depression and PINPOINT pupils. Naloxone reverses it — but it is short-acting, so re-sedation must be anticipated, especially with long-acting opioids (methadone).

Recognise

  • Reduced consciousness, slow shallow breathing, pinpoint (miotic) pupils
  • Hypoventilation/hypoxia, hypotension; track marks/patches/history
  • Methadone: prolonged effect + QT prolongation

Red flags

  • Apnoea/severe hypoventilation; re-sedation after naloxone wears off (esp. methadone/modified-release)

Differentials & how to tell them apart

Pontine strokepinpoint pupils + coma but focal signs/imaging, no naloxone response
Clonidine/organophosphateother causes of miosis; cholinergic features for organophosphate
Hypoglycaemiacheck glucose
Other sedative overdosepupils not pinpoint, no naloxone response

Investigations

Clinical (the toxidrome). ABG, glucose, ECG (methadone QT); urine toxicology; consider co-ingestants/paracetamol.

Management

Titrated naloxone (repeat/infuse for long-acting opioids) + airway/ventilation support

  1. 1Support airway/breathing (BVM oxygen); give titrated naloxone to restore adequate respiration (start low in opioid dependence to avoid acute withdrawal).Gate: Naloxone is SHORT-ACTING — with long-acting opioids (e.g. methadone, modified-release) anticipate re-sedation and use a naloxone infusion + prolonged observation
  2. 2Observe for re-sedation; treat complications; refer to drug services / safeguard; check ECG if methadone (QT).
Naloxone — titrate IV/IM 400 mcg (smaller in dependence to avoid acute withdrawal); repeat; infusion if long-acting opioid
Airway/ventilatory support — bag-valve-mask oxygen for apnoea while naloxone works

Key points

Pinpoint pupils + low RR + low GCS = opioids. Naloxone half-life is shorter than most opioids — never discharge early after a single dose.

Monitor & prognosis

Respiratory rate/SpO2, GCS, repeated naloxone need; ECG if methadone.

Excellent with ventilation + naloxone; deaths are from unobserved re-sedation.

Source: TOXBASE; BNF (naloxone)