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Opioid Analgesic — Moderate to Severe Pain in Children Pregnancy: Use with caution — neonatal opioid withdrawal syndrome if used near term; short-term use acceptable for significant pain

Morphine (Paediatric)

Brand names: Oramorph, Sevredol, MST, Morphine Sulphate Injection

Adult dose

Dose: Oral: 5–20 mg every 4 hours; IV: 0.1 mg/kg every 4 hours
Route: Oral, IV, SC
Frequency: Every 4 hours (immediate-release)
Max: Titrated to response
Adult reference — see paediatric dose for weight-based dosing

Paediatric dose

Dose: Oral: 0.1–0.3 mg/kg every 4 hours; IV: 0.05–0.1 mg/kg every 4 hours; IV infusion: 10–40 micrograms/kg/hour mg/kg
Route: Oral, IV bolus, IV continuous infusion, SC
Frequency: Every 4 hours (bolus); continuous (infusion)
Max: IV bolus: 15 mg per dose (>12 years); neonates and infants: use lower end with respiratory monitoring
BNFc: neonates — 50–100 micrograms/kg every 6 hours IV (with respiratory monitoring — highly sensitive to respiratory depression); 1–6 months — 100–200 micrograms/kg every 6 hours IV; 6 months–12 years — 100–200 micrograms/kg every 4 hours oral. Antidote: naloxone. Liquid available as 10 mg/5 mL and 100 mg/5 mL — confirm concentration before dosing.

Dose adjustments

Renal

Reduce dose and extend interval in renal impairment — active metabolite morphine-6-glucuronide accumulates; CrCl <30: consider alternative opioid (fentanyl preferred)

Hepatic

Use with caution — hepatically metabolised; reduce dose in hepatic impairment

Paediatric weight-based calculator

BNFc: neonates — 50–100 micrograms/kg every 6 hours IV (with respiratory monitoring — highly sensitive to respiratory depression); 1–6 months — 100–200 micrograms/kg every 6 hours IV; 6 months–12 years — 100–200 micrograms/kg every 4 hours oral. Antidote: naloxone. Liquid available as 10 mg/5 mL and 100 mg/5 mL — confirm concentration before dosing.

Clinical pearls

  • Antidote: naloxone — for respiratory depression: 10 micrograms/kg IV in children (repeat every 2–3 minutes, titrate to respiration — not to full reversal in opioid-dependent patients); 400 micrograms IM if IV access not available
  • Morphine-6-glucuronide (M6G) is the active metabolite — 13× more potent at mu-opioid receptor than morphine; accumulates in renal failure causing prolonged effect — use fentanyl (no active metabolites) if CrCl <30 mL/min
  • Neonates: immature blood-brain barrier and reduced hepatic glucuronidation — highly sensitive; start at lowest dose with respiratory monitoring; AVOID in premature neonates without ventilatory support
  • Histamine release: avoid rapid IV bolus — dilute and give over 15–20 minutes to reduce histaminergic hypotension and flushing

Contraindications

  • Respiratory depression
  • Acute asthma attack
  • Paralytic ileus
  • Raised intracranial pressure without ventilation

Side effects

  • Respiratory depression (most dangerous — dose-dependent)
  • Nausea and vomiting
  • Constipation
  • Pruritus
  • Sedation
  • Urinary retention
  • Miosis
  • Histamine release (flushing, hypotension — especially rapid IV)

Interactions

  • CNS depressants — additive sedation and respiratory depression
  • MAOIs — severe adverse reactions (hyperpyrexia, rigidity) — avoid for 2 weeks after MAOI
  • Benzodiazepines — FDA/MHRA warning: combined opioid + benzodiazepine significantly increases fatal respiratory depression risk

Monitoring

  • Respiratory rate and SpO2 (continuous in IV use)
  • Sedation score (COMFORT-B or FLACC scale)
  • Pain scores
  • Naloxone availability at bedside
  • Renal function (M6G accumulation)

Reference: BNF for Children; APPM Paediatric Palliative Care Formulary; NICE NG159 (Palliative Care); WHO Pain Ladder Paediatric Adaptation. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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