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Opioid Analgesic — Patient-Controlled Analgesia Pregnancy: UK SPC §4.6 — use during pregnancy or lactation is not recommended (§4.3 lists this explicitly). Pregnancy: regular use during pregnancy may cause drug dependence in the foetus, leading to withdrawal symptoms in the neonate; if opioid use is required for a prolonged period, advise the patient of the risk of neonatal opioid withdrawal syndrome and ensure appropriate treatment will be available. There are no adequate data from use in pregnant women and animal studies have shown reproductive toxicity. Administration during labour may depress respiration in the neonate and an antidote for the child should be readily available; newborns whose mothers received opioid analgesics during pregnancy should be monitored for signs of neonatal withdrawal (abstinence) syndrome, and treatment may include an opioid and supportive care. Breast-feeding: administration to nursing women is not recommended, as morphine may be secreted in breast milk and may cause respiratory depression in the infant. Fertility: animal studies have shown that morphine may reduce fertility.

Morphine (PCA — Post-Operative Pain)

Brand names: Morphine Sulfate

Morphine delivered by patient-controlled analgesia (PCA) is a mainstay of moderate-to-severe post-operative pain management, allowing the patient to self-administer small intravenous bolus doses within preset safety limits.

Adult dose

Dose: INTRAVENOUS PATIENT-CONTROLLED ANALGESIA (PCA) — adults and children over 12 years. The product is formulated for use by the intravenous route in PCA systems, at 1 mg/ml. LOADING DOSE: typically between 1 mg and 10 mg of morphine sulfate (maximum 15 mg) given by intravenous infusion over four or five minutes; the loading dose used will depend upon the patient's diagnosis and condition. PCA DEMAND DOSE: an initial demand dose of 1 mg with a lockout period of 5 to 10 minutes is recommended. Dosages may vary depending on the loading dose, the tolerance and condition of the patient, and whether a background infusion of morphine is being given. There is considerable variation in analgesic requirements among patients, so individualised treatment strategies are required, and dosage should be based on the severity of the pain and the response and opiate tolerance of the patient.
Route: Intravenous, via a patient-controlled analgesia (PCA) system. For intravenous injection; the product should NOT be diluted before use, and should be visually inspected prior to use — only clear solutions practically free from particles should be used. §4.2: PCA 'must only be carried out in departments and by staff who are trained and have experience of the system', patient selection must ensure the patient is capable of understanding and following the instructions of the medical/nursing staff, and the specific department or unit protocols must be covered to ensure aseptic transfer of the contents of the vial to the PCA system.
Frequency: Demand dose on patient demand, with a lockout period of 5 to 10 minutes between permitted demands. The loading dose is given once, over four or five minutes, before the PCA is handed to the patient.
Max: Loading dose maximum 15 mg of morphine sulfate IV (§4.2) — this is the ONLY numeric ceiling the SPC states, and it applies to the loading dose alone. The SPC states NO maximum for the PCA demand dose, no background infusion rate, and no 4-hour or 24-hour cumulative limit; those must come from the local acute pain service / PCA protocol.
That hold was recorded because the bundle then held only ORAL labelling ('Morphine 10mg/5ml Oral Solution' and a US oral tablet label), from which no PCA parameter could be taken. The bundle now holds the UK SPC for 'Morphine Sulfate 1 mg/ml solution for injection', whose §4.2 opens 'Morphine Sulfate 1 mg/ml solution for injection is formulated for use by the intravenous route in Patient Controlled Analgesia (PCA) systems' — the exact indication, route and delivery system this page exists to describe. Every figure above comes from that §4.2, which was retrieved complete. WHAT IS STILL NOT SOURCED: the SPC acknowledges that a background infusion may be running but gives no background infusion RATE, and gives no 4-hour or 24-hour limit — do not infer either. US labelling in this bundle is for oral morphine sulfate and was not used. NO ORAL FIGURE HAS BEEN CARRIED ACROSS; oral doses must never be transposed to the intravenous route. ELDERLY: morphine doses need to be reduced in elderly patients (§4.2); §4.4 adds that a dose reduction may also be appropriate in hypothyroidism and in renal and chronic hepatic disease. FIRST HOURS: the patient should be specifically monitored for pain, sedation and respiratory rate during the first few hours of treatment to ensure that the dosage regimen is suitable. DURATION AND STOPPING: the duration of treatment should be kept to a minimum and the product should not be used longer than necessary, although dependence and tolerance are not generally a problem when morphine is used legitimately in patients with opioid-sensitive pain; an abstinence syndrome may be precipitated if opioid administration is suddenly discontinued, so the dose should be gradually reduced prior to discontinuation. Before initiating treatment a strategy for ending treatment should be discussed with the patient to minimise the risk of addiction and drug withdrawal syndrome, and a treatment strategy including duration, goals and a plan for end of treatment should be agreed in accordance with pain management guidelines. In the absence of adequate pain control, consider the possibility of hyperalgesia, tolerance and progression of underlying disease. PAEDIATRIC: §4.2 'Use in children: Not recommended for children under 12 years.' Children over 12 years are covered by the adult regimen above, so paedDose is null.

Dose adjustments

Renal

Contraindicated in moderate to severe renal impairment (glomerular filtration rate <20 ml/min) — §4.3. §4.4 adds that, as with other narcotics, a dose reduction may be appropriate in patients with renal disease.

Hepatic

Contraindicated in severe or acute liver failure — §4.3. §4.4 adds that a dose reduction may be appropriate in chronic hepatic disease.

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

  • Hypersensitivity to the active substance, to other opioid preparations or to any of the excipients listed in section 6.1
  • Respiratory depression; obstructive airways disease; excessive bronchial secretions; during a bronchial asthma attack; or heart failure secondary to chronic lung disease
  • Head injury; raised intra-cranial pressure
  • Coma
  • Convulsion disorders
  • Ulcerative colitis
  • Presence of a risk of paralytic ileus
  • Biliary and renal tract spasm
  • Acute alcoholism
  • Phaeochromocytoma
  • Moderate to severe renal impairment (glomerular filtration rate <20 ml/min)
  • Severe or acute liver failure
  • Patients receiving monoamine oxidase inhibitors, or within two weeks of discontinuing such treatment
  • Use during pregnancy or lactation is not recommended (§4.3)
  • Not recommended for children under 12 years (§4.2)

Side effects

  • The side-effects most commonly seen with morphine and other opioids are respiratory depression, nausea, vomiting, constipation, drowsiness and confusion. With long-term use these symptoms generally lessen, although constipation frequently persists
  • Respiratory — bronchospasm (in association with anaphylaxis), inhibition of cough reflex, and central sleep apnoea syndrome. Opioids can cause sleep-related breathing disorders including central sleep apnoea and sleep-related hypoxaemia, and opioid use increases the risk of central sleep apnoea in a dose-dependent fashion; in patients who present with it, consider decreasing the total opioid dosage
  • Immune — anaphylactic and anaphylactoid reactions have been reported rarely
  • Psychiatric — drug dependence, restlessness, mood changes, hallucinations, delirium, disorientation, excitation, agitation, sleep disturbance
  • Nervous system — headache, vertigo, euphoria, dysphoria, dizziness, taste disturbances, seizures, paraesthesia, raised intracranial pressure, hyperhidrosis; allodynia and hyperalgesia have been reported
  • Eye — visual disturbances, nystagmus, miosis
  • Cardiac and vascular — bradycardia, tachycardia, palpitations, syncope; orthostatic hypotension, hypotension, hypertension, facial flushing, oedema
  • Gastrointestinal and hepatobiliary — dyspepsia, paralytic ileus, abdominal pain, anorexia, dry mouth, pancreatitis; biliary spasm and spasm of the sphincter of Oddi
  • Skin — rashes, urticaria, pruritus, and acute generalised exanthematous pustulosis (AGEP)
  • Musculoskeletal — muscle fasciculation, myoclonus, rhabdomyolysis, muscle rigidity
  • Renal and urinary — difficult micturition, ureteric spasm, urinary retention
  • Endocrine and reproductive — long-term use of opioid analgesics can cause adrenal insufficiency, and hypogonadism in both men and women, which can lead to amenorrhoea, reduced libido, infertility, depression and erectile dysfunction; exacerbation of pancreatitis
  • General — hypothermia, malaise, asthenia, pain and irritation at the injection site
  • High doses may produce respiratory depression and hypotension, with deepening coma; convulsions may occur particularly in infants. Long-term use has been associated with abnormal pain sensitivity (hyperalgesia), and tolerance and psychological and physical dependence may occur
  • NOTE: §4.8 was cut at the source-fetch limit within the drug-dependence-and-withdrawal paragraph — this list reproduces what was retrieved and may not be complete

Interactions

  • Monoamine oxidase inhibitors — contraindicated concurrently or within two weeks of discontinuing such treatment (§4.3)
  • Other opioid analgesics such as codeine, administered orally or by some other route — increases the CNS depressant effect of morphine (§4.4)
  • Sedative medicines such as benzodiazepines or related drugs — concomitant use may result in sedation, respiratory depression, coma and death. Concomitant prescribing should be reserved for patients for whom alternative treatment options are not possible; if prescribed together, use the lowest effective dose for the shortest possible duration, follow the patient closely for signs and symptoms of respiratory depression and sedation, and inform patients and their caregivers to be aware of these symptoms (§4.4)
  • This interaction list may be incomplete — check the full SPC.

Monitoring

  • Monitor specifically for pain, sedation and respiratory rate during the first few hours of treatment, to ensure that the dosage regimen is suitable (§4.2)
  • PCA must only be carried out in departments and by staff trained and experienced in the system, and patient selection must confirm the patient can understand and follow the instructions of the medical/nursing staff (§4.2)
  • Frequent physician-patient contact during treatment to evaluate the need for continued treatment, consider discontinuation and adjust dosages if needed (§4.2)
  • Taper before stopping — an abstinence syndrome may be precipitated if opioid administration is suddenly discontinued (§4.2)
  • Assess risk of Opioid Use Disorder before and during treatment — risk is increased in patients with a personal or family history of substance use disorders including alcohol use disorder, in current tobacco users, and in patients with a personal history of other mental health disorders such as major depression, anxiety and personality disorders (§4.4)
  • Post-operative caution — use with caution post-operatively following total joint arthroplasty (colonic pseudo-obstruction) (§4.4)
  • Use with caution and consider a lower dose in debilitated patients and in adrenocortical insufficiency, hypopituitarism, prostatic hypertrophy, shock, diabetes mellitus, diseases of the biliary tract, myasthenia gravis, cardiac arrhythmias, excessive obesity, hypotension and severe cardiac failure (§4.4)
  • NOTE: §4.4 was cut at the source-fetch limit within the Opioid Use Disorder paragraph — read the remainder from the SPC

Clinical monograph

How it works

Morphine is a strong agonist at mu-opioid receptors in the central nervous system, reducing nociceptive transmission and altering the affective response to pain.

Prescribing in practice

  • Opioid-induced respiratory depression is the principal hazard — programme an appropriate bolus, lockout interval and any background infusion carefully, ensure only the patient activates the handset (never staff or family), and have naloxone and monitoring immediately available.
  • Set the PCA programme on a dedicated infusion pump with the giving set protected by an anti-reflux/anti-siphon valve, and avoid concurrent systemic opioids or sedatives unless explicitly co-prescribed and monitored.
  • Morphine and its active metabolite accumulate in renal impairment, so reduce reliance on PCA morphine or consider an alternative opioid in significant renal dysfunction or the frail elderly.

Monitoring

Monitor sedation score, respiratory rate, oxygen saturation, pain score and cumulative dose regularly, with closer observation after any programme change.

Counselling the patient

  • Press the handset when you feel pain — you cannot easily overdose because of the built-in lockout.
  • Only you should press the button, never a visitor or nurse on your behalf.
  • Tell staff promptly if you feel very drowsy, sick or your pain is not controlled.

Evidence & guidelines

PCA morphine is well established for post-operative analgesia and is supported by long-standing anaesthetic and acute pain service practice.

Reference: ANZCA Acute Pain Management Guidelines; RCoA Acute Pain Handbook; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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