When to use the “unspecified” label

Use this label when clinical features clearly point to opioid intoxication, withdrawal or problematic opioid use but the specific agent or formulation is unknown at presentation — a common situation with illicit supplies and counterfeit pills. It is a working diagnosis prompting immediate treatment and linkage to addiction care.

Key clinical presentations

• Opioid intoxication/overdose: miosis (pinpoint pupils), decreased consciousness, respiratory depression (slow shallow breathing), hypoxia and bradycardia.
• Withdrawal: yawning, lacrimation, rhinorrhoea, piloerection, nausea, vomiting, diarrhoea, myalgias, anxiety, insomnia and severe craving.
• Chronic opioid use disorder: persistent craving, loss of control, tolerance, continued use despite harm and functional impairment.

Immediate assessment — ABCs and focused observations

1. Airway, Breathing, Circulation — assess respiratory rate, oxygen saturation and level of consciousness (GCS).
2. Rapid observations: RR <12, hypoxia, pinpoint pupils support opioid toxicity but may be absent with some synthetic opioids or co‑ingestants.
3. History: time/route/amount of use (if available), co‑ingestants, previous overdose or treatments, pregnancy status and comorbidities.
4. Collateral: friends, EMS, scene clues (pill bottles, patches, syringes) and bystander reports are often decisive.

Naloxone — use and practical tips

• Naloxone is life‑saving for suspected opioid respiratory depression — give intramuscular, intravenous or intranasal titrated doses until adequate ventilation restored. Start conservatively to avoid abrupt withdrawal when possible (eg, 0.04–0.4 mg IV titrated upward), but do not delay if patient is apnoeic.
• In cases of potent synthetic opioids (eg, fentanyl analogues), repeated doses or an infusion may be required; monitor closely for re‑sedation as naloxone effect wanes.
• Be prepared for precipitated withdrawal — counsel companions and be ready to provide symptomatic relief and link to addiction services after stabilization.

Investigations — targeted tests

• Immediate: pulse oximetry, ECG, capillary glucose, ABG if respiratory compromise suspected.
• Blood tests: CBC, electrolytes, renal & liver function, creatine kinase if suspected rhabdomyolysis, troponin if chest pain.
• Toxicology: urine drug screen and serum assays where available — many synthetic opioids may be missed on routine screens.
• Imaging: chest x‑ray if aspiration suspected; CT head for head injury or focal deficits.

Managing opioid withdrawal

• Symptom relief: alpha‑2 agonists (clonidine or lofexidine where available) reduce autonomic symptoms; antiemetics, antidiarrhoeals (loperamide), NSAIDs for myalgia and sleep hygiene aid comfort.
• For moderate‑to‑severe dependence, opioid agonist therapy (OAT) with methadone or buprenorphine is first‑line for induction and maintenance—offer as soon as feasible and discuss options with patient.
• Rapid opioid detoxification is discouraged due to risk; planned, supervised withdrawal or OAT initiation is safer and more effective for long‑term outcomes.

Initiating Opioid Agonist Treatment (OAT)

• Methadone: effective for maintenance but requires supervised dosing and careful QTc monitoring in higher doses.
• Buprenorphine (± naloxone): partial agonist with favourable safety; avoid precipitated withdrawal by ensuring appropriate timing after last opioid and using micro‑induction protocols when necessary.
• OAT initiation should be accompanied by psychosocial support, harm reduction (needle/syringe programs), naloxone distribution and linkage to social services.

Harm reduction & prevention

• Provide take‑home naloxone kits and train peers/family in overdose recognition and rescue breathing/naloxone use.
• Needle/syringe programs, safe injecting advice, access to testing (HIV, hepatitis B/C) and vaccination where appropriate.
• Educate about risks of adulterants (eg, fentanyl) and recommend not using alone, test‑small‑amount strategies and checking drug‑checking services if available.

Special populations & cautions

• Pregnancy: OAT (methadone or buprenorphine) is recommended over detox in pregnancy—coordinate obstetric and addiction care.
• Polysubstance use: co‑ingested benzodiazepines or alcohol increase respiratory depression risk—manage airway and avoid high naloxone doses without ventilatory support.
• Fentanyl and analogues: expect higher naloxone requirements and possible prolonged monitoring due to re‑sedation risk.

Key takeaways

• When the opioid agent is unknown, prioritise airway and breathing — use naloxone titrated to effect and monitor for re‑sedation.
• Opioid withdrawal is best managed with symptom relief and offering OAT (methadone or buprenorphine) for long‑term treatment.
• Harm reduction (naloxone distribution, needle/syringe programs, drug‑checking where available) saves lives and should be standard practice.
• Special populations (pregnancy, polysubstance use, fentanyl exposure) require tailored approaches and multidisciplinary care.