Morphine
morphine sulfate IR
Pronunciation: MOR-feen
“Morphing”
opioids constrict pupils
What it isFull mu opioid agonist and the reference standard; severe and cancer pain.
Why it mattersEvery route, cheap, and all other opioids are compared to it.
What it changesActive metabolites accumulate in renal impairment and cause myoclonus and sedation — use hydromorphone or fentanyl instead below eGFR 30.
Pearls
- Little added benefit above 50 MME/day; overdose risk climbs.
- Alcohol can dump ER capsules: rapid morphine release.
- Low-dose ER for refractory dyspnea: inconsistent benefit.
- 24-hour ER oral morphine: off-label OUD maintenance alternative to methadone.
Morphine prescription history
Animated chart of estimated U.S. prescriptions per year, Opioid analgesics (1900–2026). Morphine enters in 1900 (estimated).
FDA-approved for
- pain (~1941)
Off-label
- dyspnea in palliative care
Classes and tags
Clinical profile
Legacy pregnancy categoryC
Defining liabilityRespiratory depression, dependence and overdose; risk rises sharply with sedatives or impaired clearance.
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Acute or chronic pain (severe, requiring an opioid; alternatives inadequate) | Adults | 15–30 mg every 4 hours PRN (lowest effective dose) | Titrate to individual response | Undefined |
| Acute pain (severe, requiring an opioid; alternatives inadequate) | Pediatric ≥50 kg able to swallow tablets | 15 mg every 4 hours PRN (lowest effective dose) | Titrate to individual response | Initial dose ≤30 mg |
Titration Individually titrate based on response.
Renal Substantially renally excreted; start with lower dosage and titrate slowly.
Hepatic Cirrhosis: start with lower than usual dosage and titrate slowly.
Conversion from parenteral: 3–6 mg oral ≈ 1 mg parenteral morphine.
Instructions
- Do not abruptly discontinue in physically dependent patients; taper by 10–25% of total daily dose every 2–4 weeks
- Pediatric <50 kg: not recommended (dose cannot be achieved with available tablet strengths); consider another morphine product
- Discuss/consider naloxone access
Available strengths
- tab 15, 30 mg
- ER cap 10, 20, 30, 45, 50, 60, 75, 80, 90, 100, 120 mg
- ER tab 15, 30, 60, 100, 200 mg
- sol 20, 100 mg/5 mL
- sol 2, 4, 10 mg/mL
- tincture 1 g/100 mL
- tincture 10 mg/mL
- supp 5, 10, 20, 30 mg
- + 1 other marketed form not shown
Contraindications
- Significant respiratory depression
- Acute or severe bronchial asthma in an unmonitored setting or without resuscitative equipment
- Concurrent MAOI use or within the last 14 days
- Known or suspected GI obstruction, including paralytic ileus
Cautions
- Life-threatening respiratory depression
- Adrenal insufficiency
- Severe hypotension
- Use in increased intracranial pressure/head injury
- Opioid-induced hyperalgesia
Adverse reactions
- Constipation
- Nausea
- Somnolence
- Lightheadedness/dizziness
- Vomiting
- Sweating
- Respiratory depression
Pregnancy Prolonged use can cause neonatal opioid withdrawal syndrome; no clear malformation association.
Lactation Present in breast milk; monitor infant for excess sedation and respiratory depression.
Cost
| Strength | #/mo | generic $/unit | CostPlus | |
|---|---|---|---|---|
| 15 mg | tab | per unit | $0.23/ea | not offered |
| 30 mg | tab | per unit | $0.34/ea | not offered |
Other forms: Morphine ER capsules (KADIAN) · Morphine ER tablets (MS CONTIN)
Generic entry1986
Serotonicity
This drug is routinely called serotonergic. By Gillman’s human-effect criteria it does not raise serotonin in the synapse.
Opioid effects and respiratory/CNS-depressant interactions remain important, but this drug is not a clinically significant SRI by the Gillman framework.
Label contraindicationConcurrent MAOI use or within the last 14 days. The label governs prescribing; Gillman’s point concerns serotonin toxicity only.
Gillman’s four human testsA measurable SERT affinity that fails all four is not clinical serotonicity.
- Retarded orgasm
- Efficacy in OCD and cataplexy
- Clonus and hyperreflexia in single-drug overdose
- Serotonin toxicity when combined with an MAOI
Non-elevating actionNone recorded
Evidence confidenceHigh
Background: what serotonicity is · what is and is not an SRI · what counts as a relevant MAOI.
Active metabolites
Open Morphine in the interactive console ↗
Memory aids: interaction avatars
Open Morphine in the interactive console ↗
Self-check
- Why is morphine problematic in renal impairment?
Active metabolites accumulate. - What alternative opioids are named below eGFR 30?
Hydromorphone or fentanyl.