Section 19 · Monograph
Morphine
Reviewed Nov 2026FDA label
MS Contin / Roxanol / genericOpioid agonist (CII)
- Forms
- IR tab: 15, 30mg | ER tab: 15, 30, 60, 100, 200mg | Soln: 10mg/5mL, 20mg/mL | Inj: 2, 4, 10mg/mL
- Dose
- Opioid-naive pain or dyspnea: 2.5-10mg PO every 4h as needed (start low in frail or renally impaired); IV/SC 1-5mg every 3-4h; titrate to effect
- MOA
- μ-opioid receptor agonism
Black Box Warning
- Addiction, abuse and misuse; life-threatening respiratory depression; accidental ingestion; neonatal opioid withdrawal syndrome; risks from concomitant use with benzodiazepines or other CNS depressants; available under an opioid analgesic REMS
Indications
- Management of acute and chronic pain severe enough to require an opioid analgesicFDA-labeled
- Palliative relief of dyspnea (off-label, widely used)FDA-labeled
Mechanism of Action
- Full mu-opioid receptor agonist producing analgesia, euphoria, and reduced sense of dyspnea; hepatic glucuronidation to active metabolites cleared by the kidney
Full Dosing
Adult / usual
- Opioid-naive adults: 2.5-10mg PO every 4 hours as needed (label starting dose 15-30mg IR); IV/SC 1-5mg every 3-4 hours; start low in frail, older or renally impaired patients and titrate to effect
- ER tablets only for opioid-tolerant patients; do not crush or chew
Renal
- Active metabolites (M3G, M6G) accumulate in renal failure — prefer hydromorphone or fentanyl in significant CKD
Contraindications
- Significant respiratory depression
- Acute or severe bronchial asthma in an unmonitored setting
- Known or suspected gastrointestinal obstruction including paralytic ileus
- Hypersensitivity to morphine
Drug Interactions
- Benzodiazepines, gabapentinoids, alcohol and other CNS depressants: profound sedation and respiratory depression
- MAO inhibitors and serotonergic drugs: serotonin syndrome risk
- Anticholinergics: constipation and urinary retention
Adverse Effects
- Constipation (universal — start a bowel regimen)
- Nausea, sedation, confusion
- Respiratory depression
- Myoclonus and opioid-induced neurotoxicity with high doses or renal failure
- Pruritus, urinary retention
Monitoring Parameters
- Sedation, respiratory rate and pain control
- Bowel function
- Renal function; signs of neurotoxicity (myoclonus, delirium)
Pregnancy & Lactation
- Neonatal opioid withdrawal syndrome with prolonged use in pregnancy
- Present in milk; monitor infants for sedation