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Pharmacological Acute Pain Management

Last updated 1 Jun 2026 · Pain & analgesia

📋 Key Information Summary

📋
  • Acute pain management in Australia should follow the WHO analgesic ladder: non-opioids (step 1) → weak opioids (step 2) → strong opioids (step 3), with adjuvants at any step.
  • Drug choice depends on pain severity, route suitability, pain mechanism (nociceptive vs neuropathic), comorbidities, and renal/hepatic function.
  • Paracetamol is first-line for mild-to-moderate acute pain; IV formulation (Perfalgan®) is used when oral route is unavailable; maximum 4 g/day in adults (reduced in low body weight and hepatic impairment).
  • NSAIDs are effective anti-inflammatory analgesics but carry cardiovascular, renal, and gastrointestinal risks; use the lowest effective dose for the shortest duration.
  • Opioids are reserved for moderate-to-severe acute pain or when non-opioid analgesia is insufficient; prescribe at the lowest effective dose and review within 48 hours.
  • Combining paracetamol with an NSAID provides additive analgesia and is often opioid-sparing (multimodal analgesia).
  • Short-acting opioids (oxycodone IR, morphine IR) are preferred for acute pain; long-acting formulations should not be initiated in opioid-naïve patients for acute pain.
  • Adjuvants such as gabapentinoids, ketamine, dexamethasone, and regional anaesthesia techniques enhance analgesia and reduce opioid consumption.
  • Patients with renal impairment (eGFR <30 mL/min) require dose reduction or avoidance of NSAIDs, adjusted opioid doses, and caution with gabapentinoids.
  • Hepatic impairment mandates reduced paracetamol dosing (≤2 g/day in severe disease) and avoidance of NSAIDs where possible.
  • Elderly patients are at increased risk of opioid toxicity, NSAID-related GI bleeding, and falls; start low, go slow, and review regularly.
  • Opioid stewardship principles — clear indication, documented plan, time-limited prescription, patient education — are embedded in NSQHS Standards and state regulatory requirements.
  • Aboriginal and Torres Strait Islander patients may face barriers including remote access, health literacy, and cultural considerations; individualised, culturally safe pain plans are essential.

Introduction & Australian Epidemiology

Acute pain is the most common presenting complaint in Australian emergency departments and primary care, affecting over 7 million ED presentations annually. Effective pharmacological management reduces morbidity, shortens hospital stays, and prevents the transition of acute pain to chronic pain. Australian practice is guided by Therapeutic Guidelines (eTG), the Australian and New Zealand College of Anaesthetists (ANZCA) Faculty of Pain Medicine, and the National Safety and Quality Health Service (NSQHS) Standards.

The WHO analgesic ladder remains the foundational framework: non-opioid analgesics (paracetamol, NSAIDs) form the base, weak opioids (codeine, tramadol) occupy the middle tier, and strong opioids (morphine, oxycodone, fentanyl) are reserved for severe pain. Multimodal analgesia — combining agents with complementary mechanisms — is now the standard of care, reducing opioid requirements and improving outcomes.

Australia faces particular challenges in acute pain management including opioid-related harms (approximately 3,000 opioid-related deaths per year nationally), disparities in access for rural and remote communities, and the need for culturally safe care for Aboriginal and Torres Strait Islander peoples. The Pharmaceutical Benefits Scheme (PBS) supports equitable access to first-line agents while regulatory controls on opioids (Schedule 8) aim to balance availability with safety.

⚠️
Prescribing principle: Always identify the pain mechanism (nociceptive vs neuropathic vs mixed), assess severity on a validated scale (e.g., NRS 0–10), and select the least invasive effective regimen. Reassess at defined intervals and de-escalate as pain improves.

Paracetamol (Acetaminophen)

Paracetamol is the most widely used analgesic in Australia and the recommended first-line agent for mild-to-moderate acute pain (WHO step 1). Its mechanism involves central inhibition of COX-2 and modulation of descending serotonergic inhibitory pathways. It has minimal anti-inflammatory activity, a favourable safety profile at therapeutic doses, and is available in oral, IV, and rectal formulations.

Available Formulations

Formulation Route Strengths Brand(s) PBS Status
Tablets / caplets Oral 500 mg, 665 mg SR Panadol®, Panadol Osteo® General Benefit (OTC)
Suspension Oral 24 mg/mL, 48 mg/mL Panadol Children's® General Benefit
Suppositories Rectal 125 mg, 250 mg, 500 mg, 1 g Paracetamol Alphapharm General Benefit
IV infusion Intravenous 10 mg/mL (100 mL bag) Perfalgan® Restricted Benefit

Dosing — Adult

💊
Paracetamol
Panadol® · Panadol Osteo® · Perfalgan® · Non-opioid analgesic
Adult dose (oral) 1 g PO QID (max 4 g/24 h); or 665 mg SR PO TDS (max 3.9 g/24 h)
Adult dose (IV) 1 g IV Q6H (max 4 g/24 h); 100 mL bag infused over 15 min
Paediatric dose (oral) 15 mg/kg PO Q4–6H (max 60 mg/kg/24 h, not exceeding 4 g/24 h)
Paediatric dose (IV) 15 mg/kg IV Q6H (max 60 mg/kg/24 h); neonates 7.5 mg/kg Q6–8H
Renal adjustment eGFR >10: no adjustment; extend interval to Q6–8H if eGFR <10 (limited data)
Hepatic adjustment Max 2 g/day in severe hepatic impairment or chronic liver disease
PBS status ✔ PBS General Benefit
🚨
Hepatotoxicity warning: Acute overdose (>150 mg/kg or >10 g in adults) causes fulminant hepatic failure. N-acetylcysteine (NAC) is the antidote — administer within 8 hours of ingestion using the Australian RCH/Toxicology protocol. Chronic supratherapeutic dosing (often unintentional, especially with combination analgesics) is an under-recognised cause of hepatotoxicity.

Key Clinical Points

  • Paracetamol IV provides equivalent analgesia to oral at steady state; advantage is use when oral route is unavailable (post-operative nausea, fasting, intubation).
  • Regular (around-the-clock) dosing is superior to PRN dosing for maintaining therapeutic plasma levels.
  • No clinically significant antiplatelet effect — safe to continue peri-operatively.
  • Available OTC without prescription; counsel patients to check all concurrent medicines for hidden paracetamol content (e.g., combination codeine preparations, cold-and-flu products).
  • Body weight <50 kg: reduce total daily dose proportionally (max 50 mg/kg/day).

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

NSAIDs are cornerstone analgesics for acute musculoskeletal and inflammatory pain. They inhibit cyclooxygenase enzymes (COX-1 and COX-2), reducing prostaglandin synthesis and thereby decreasing inflammation, pain, and fever. NSAIDs are particularly effective when inflammation is a major pain driver (e.g., fractures, dental pain, post-operative pain, renal colic).

Commonly Used NSAIDs in Australia

💊
Ibuprofen
Nurofen® · Brufen® · Non-selective NSAID
Adult dose 200–400 mg PO TDS–QID (max 2.4 g/day for analgesia; 1.2 g/day OTC)
Paediatric dose 5–10 mg/kg PO TDS–QID (max 30 mg/kg/day; from 3 months of age)
Renal adjustment Avoid if eGFR <30 mL/min; use with caution if eGFR 30–60
Hepatic adjustment Avoid in severe hepatic impairment
PBS status ✔ PBS General Benefit
💊
Naproxen
Naprosyn® · Inza® · Non-selective NSAID
Adult dose 250–500 mg PO BD–TDS (max 1 g/day for acute pain)
Paediatric dose 5–7 mg/kg PO BD (from 2 years; juvenile arthritis indication)
Renal adjustment Avoid if eGFR <30 mL/min
PBS status ✔ PBS General Benefit
💊
Celecoxib
Celebrex® · Selective COX-2 inhibitor
Adult dose 100–200 mg PO BD (max 400 mg/day for acute pain)
Paediatric dose Not routinely recommended <18 years (limited data)
Renal adjustment Avoid if eGFR <30 mL/min
Hepatic adjustment Reduce dose 50% in moderate hepatic impairment; avoid in severe
PBS status ✔ PBS General Benefit
💊
Diclofenac
Voltaren® · Non-selective NSAID
Adult dose (oral) 25–50 mg PO TDS (max 150 mg/day for acute pain; reduce to 75 mg/day)
Adult dose (IM) 75 mg IM as a single dose (post-operative)
Paediatric dose 1 mg/kg PO TDS (max 3 mg/kg/day); from 1 year
Renal adjustment Avoid if eGFR <30 mL/min
PBS status ✔ PBS General Benefit
💊
Ketorolac
Toradol® · Non-selective NSAID (parenteral)
Adult dose (IV/IM) 10–30 mg IV/IM stat, then 10–30 mg Q6H (max 90 mg/day; 60 mg if age >65 or weight <50 kg); max 5 days
Paediatric dose 0.5 mg/kg IV (max 15 mg); >6 months, specialist guidance
Renal adjustment Contraindicated if eGFR <30 mL/min
PBS status ⚠ PBS Authority Required
🚨
Critical safety information: NSAIDs cause a dose-dependent increase in cardiovascular events (MI, stroke), gastrointestinal ulceration/haemorrhage, and acute kidney injury. They are contraindicated in the third trimester of pregnancy (premature closure of ductus arteriosus). Always co-prescribe a PPI (e.g., omeprazole 20 mg PO daily) in patients at GI risk. NSAIDs should generally be avoided in heart failure (NYHA class III–IV) and chronic kidney disease (eGFR <30).

When to Prefer a COX-2 Selective Agent

  • History of NSAID-associated GI ulceration or bleeding (with PPI co-prescription).
  • Patients on anticoagulants where GI bleeding risk is already elevated.
  • Patients at high cardiovascular risk — use with caution; naproxen may be preferred if NSAID is essential due to lower CV signal.
  • Peri-operative setting where antiplatelet effect of non-selective NSAIDs is undesirable (celecoxib has minimal antiplatelet effect).

Topical NSAIDs

Topical diclofenac (Voltaren Emulgel®) is effective for superficial musculoskeletal pain (e.g., ankle sprains, osteoarthritis of the knee/hand) with minimal systemic absorption. Apply 2–4 g to affected area QID. PBS General Benefit for osteoarthritis; available OTC for acute soft-tissue injuries.

Opioids

Opioids remain essential for moderate-to-severe acute pain unresponsive to non-opioid analgesics. They act on mu (μ), kappa (κ), and delta (δ) opioid receptors in the central and peripheral nervous systems. In Australia, all opioids except codeine (Schedule 4) are Schedule 8 (Controlled Drugs), requiring state and territory regulatory compliance for prescribing and supply.

⚠️
Opioid stewardship: Prescribe the minimum effective dose for the shortest indicated duration. Set a clear stopping criterion. Review at 48 hours. Avoid initiating long-acting opioids for acute pain in opioid-naïve patients. Discuss the risk of dependence with the patient. Comply with state/territory SafeScript real-time monitoring requirements.

Short-Acting Opioids for Acute Pain

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Morphine
MS Contin IR® · Oramorph® · Strong opioid agonist
Adult dose (oral) 5–10 mg PO Q4H PRN (opioid-naïve); titrate by 25–50% increments
Adult dose (IV/SC) 2.5–5 mg IV Q4H PRN; or 1–2 mg IV Q5min titrated in ED
Paediatric dose 0.1–0.2 mg/kg PO Q4H (max 0.5 mg/kg/dose); 0.05–0.1 mg/kg IV Q2–4H
Renal adjustment Active metabolite (M6G) accumulates — reduce dose 50% and extend interval if eGFR <30; avoid in eGFR <15 if possible
Hepatic adjustment Reduce dose 50% in severe hepatic impairment
PBS status ⚠ PBS Authority Required
💊
Oxycodone
Endone® · OxyNorm® · Strong opioid agonist
Adult dose (oral) 5–10 mg PO Q4–6H PRN (opioid-naïve); titrate as required
Paediatric dose 0.05–0.1 mg/kg PO Q4H PRN (specialist guidance recommended)
Renal adjustment Reduce dose and extend interval if eGFR <30; avoid active metabolites
Hepatic adjustment Reduce dose 50% in severe hepatic impairment
PBS status ⚠ PBS Authority Required
💊
Tramadol
Tramal® · Weak opioid + SNRI mechanism
Adult dose (oral) 50–100 mg PO Q4–6H PRN (max 400 mg/day; 300 mg/day if age >65)
Adult dose (IV) 50–100 mg IV Q6H (infuse over 20–30 min)
Paediatric dose 1–2 mg/kg PO Q6H (from 12 years); limited use in paediatrics
Renal adjustment Reduce dose 50% if eGFR <30; extend interval to Q12H if eGFR <15
Hepatic adjustment Reduce dose 50% in severe impairment; risk of serotonin toxicity with SSRIs/MAOIs
PBS status ⚠ PBS Authority Required
💊
Fentanyl
Sublimaze® (IV) · Strong synthetic opioid agonist
Adult dose (IV) 25–50 mcg IV Q1–2H PRN; or 25–50 mcg intranasal (off-label) for procedural pain
Paediatric dose (IN) 1.5 mcg/kg intranasal (single dose); onset ~5 min
Renal adjustment Safer than morphine in renal impairment — preferred IV opioid if eGFR <15
Hepatic adjustment Use with caution; dose reduction may be required
PBS status 🔴 PBS Authority Required (S8)
🚨
Opioid toxicity and dependence: All opioids cause dose-dependent respiratory depression, constipation, nausea/vomiting, sedation, and pruritus. Naloxone (Narcan®) 0.4–2 mg IV/IM/IN should be immediately available wherever opioids are administered. Tramadol lowers seizure threshold and interacts with serotonergic medications (risk of serotonin syndrome). Codeine is no longer recommended in children <12 years (TGA restriction) and is metabolised variably (CYP2D6 polymorphism) — avoid in ultra-rapid and poor metabolisers.

Codeine — Restricted Role

Codeine is a Schedule 4 prodrug requiring hepatic CYP2D6 conversion to morphine. Since 1 February 2018, codeine is no longer available OTC in Australia and requires a prescription. Due to highly variable metabolism (poor to ultra-rapid metabolisers), unpredictable analgesic efficacy, and risk of fatal respiratory depression in neonates of breastfeeding mothers who are ultra-rapid metabolisers, codeine's role has diminished. Low-dose codeine combinations (e.g., codeine 30 mg/paracetamol 500 mg) may still be prescribed for short-term acute pain at the clinician's discretion, but alternatives (paracetamol + NSAID ± tramadol) are generally preferred.

Patient-Controlled Analgesia (PCA)

PCA (typically morphine or fentanyl) is used in hospital settings for moderate-to-severe acute pain (e.g., post-surgical, trauma). Standard adult morphine PCA settings: bolus 1 mg, lockout interval 5–8 min, no continuous background infusion (to reduce respiratory depression risk). PCA is generally reserved for patients able to understand the device; nurse/patient-controlled analgesia (NCA) is used for children or cognitively impaired patients.

Adjuvant Analgesics

Adjuvant analgesics are medications whose primary indication is not pain but that have demonstrated analgesic efficacy in specific acute pain contexts. They enhance multimodal analgesia, reduce opioid requirements, and are particularly valuable for neuropathic components and peri-operative pain management.

Gabapentinoids

💊
Gabapentin
Neurontin® · Gabapentin Sandoz® · Calcium channel modulator
Adult dose (acute) 300 mg PO OD Day 1, 300 mg BD Day 2, 300 mg TDS Day 3; titrate to 300–600 mg TDS as tolerated
Peri-operative dose 300–600 mg PO 1–2 hours pre-operatively, then 300 mg TDS for 2–5 days post-op
Renal adjustment eGFR 30–59: max 300 mg BD; eGFR 15–29: 300 mg OD; eGFR <15: 300 mg alternate days
PBS status ✔ PBS General Benefit
💊
Pregabalin
Lyrica® · Calcium channel modulator
Adult dose (acute neuropathic) 75 mg PO BD, titrate to 150 mg BD within 3–7 days (max 600 mg/day)
Renal adjustment eGFR 30–60: 75–300 mg/day; eGFR 15–29: 25–150 mg/day; eGFR <15: 25–75 mg/day
PBS status ⚠ PBS Authority Required (neuropathic pain)

Sub-anaesthetic Ketamine

💊
Ketamine
Ketalar® · NMDA receptor antagonist
Adult dose (sub-anaesthetic) 0.1–0.3 mg/kg IV over 15–30 min as a single dose or infusion; in ED for acute pain refractory to opioids
Peri-operative analgesic 0.25–0.5 mg/kg IV at induction, then 0.1–0.25 mg/kg/hr for 24–48 h
Renal adjustment No significant adjustment required; use with caution in severe CKD
Key cautions Emergence reactions (co-administer midazolam 0.5–1 mg IV); avoid in uncontrolled hypertension, raised ICP, severe psychiatric illness
PBS status 🔴 Not PBS (hospital use)

Dexamethasone

💊
Dexamethasone
Decadron® · Corticosteroid adjuvant
Adult dose (peri-operative) 4–8 mg IV at induction (single dose); reduces post-operative pain, nausea, and opioid requirements
Paediatric dose 0.15 mg/kg IV (max 8 mg) at induction
Key indications Peri-operative opioid-sparing; acute nerve compression pain; oral surgery (dental); croup (paediatric)
PBS status ✔ PBS General Benefit

Lidocaine (Lignocaine)

💊
Lidocaine (IV)
Xylocaine® · Sodium channel blocker
Adult dose (IV infusion) 1–1.5 mg/kg/hr IV infusion for 24–48 h post-operatively (anaesthetist-directed)
Key indications Peri-operative opioid-sparing; abdominal surgery; chronic pain flares; ERAS protocols
Key cautions Cardiac monitoring required; avoid in severe hepatic impairment; toxicity at >5 mcg/mL
PBS status 🔴 Not PBS (hospital use)

Other Adjuvants

Agent Mechanism Acute Pain Indication Key Dose
Amitriptyline TCA — serotonergic/noradrenergic Acute neuropathic pain, post-herpetic neuralgia 10–25 mg PO nocte, titrate to 75 mg
Clonidine α₂-agonist Peri-operative adjuvant; regional anaesthesia adjunct 1–2 mcg/kg IV or 150 mcg PO pre-op
Magnesium NMDA receptor antagonist Peri-operative opioid-sparing; acute migraine 30–50 mg/kg IV at induction (max 2 g)
Paracetamol + caffeine Enhanced analgesic absorption Acute headache, dental pain 1 g paracetamol + 130 mg caffeine PO (available OTC)

Regional Anaesthesia Techniques (Adjuvant)

Regional anaesthesia is a powerful opioid-sparing adjuvant strategy. Techniques commonly used for acute pain in Australia include:

  • Fascia iliaca compartment block — hip fractures in the emergency department; reduces opioid use and delirium in elderly patients.
  • Intercostal nerve blocks / erector spinae plane (ESP) blocks — rib fractures, thoracic surgery.
  • Transversus abdominis plane (TAP) blocks — abdominal surgery, caesarean section.
  • Peripheral nerve catheter infusions — upper and lower limb surgery; managed by acute pain services.
  • Intrathecal morphine — single dose at caesarean section (100–150 mcg) or major surgery.

Pathophysiology — Nociceptive vs Neuropathic Pain

Pharmacological selection depends on understanding the pain mechanism:

Nociceptive
Somatic / Visceral
Tissue damage activates peripheral nociceptors (Aδ and C fibres). Prostaglandins, bradykinin, and substance P sensitise and transmit pain via ascending spinal pathways.
Best response: Paracetamol, NSAIDs, opioids
Neuropathic
Nerve injury / Dysfunction
Aberrant sodium channel activity, central sensitisation, and altered descending modulation. Presents as burning, shooting, allodynia, or hyperalgesia.
Best response: Gabapentinoids, TCAs, SNRIs, ketamine, lidocaine
Mixed / Central sensitisation
Nociceptive + Neuropathic
Common in chronic pain flares, cancer pain, and post-surgical pain. Central sensitisation amplifies peripheral signals.
Best response: Multimodal regimen combining agents from both categories

Risk Stratification & Pain Severity Assessment

Systematic assessment guides analgesic selection. Use a validated numeric rating scale (NRS 0–10) or visual analogue scale (VAS):

Mild
NRS 1–3
Minimal functional impairment; tolerable without significant distress.
Step 1: Paracetamol ± NSAID; non-pharmacological measures
Moderate
NRS 4–6
Interferes with function, sleep, and concentration; patient distressed.
Step 2: Paracetamol + NSAID ± weak opioid (tramadol); adjuvants
Severe
NRS 7–10
Inability to function; significant autonomic response (tachycardia, hypertension); may require parenteral analgesia.
Step 3: Strong opioids IV ± paracetamol IV ± NSAID; consider regional anaesthesia and adjuvants

Opioid Risk Assessment

Before initiating opioids for acute pain, assess:

  • History of substance use disorder (opioid, alcohol, benzodiazepine).
  • Current or past use of prescribed opioids, including dose and duration.
  • Psychiatric comorbidities (depression, anxiety, PTSD) — increased risk of persistent opioid use.
  • Age >65 — increased sensitivity to respiratory depression and falls.
  • Obstructive sleep apnoea / obesity hypoventilation syndrome — higher risk of post-operative respiratory events.
  • Renal and hepatic function affecting opioid metabolism and clearance.
  • Concurrent CNS depressants (benzodiazepines, gabapentinoids, antipsychotics).

Investigations

Baseline investigations guide safe pharmacological analgesia and monitor for complications:

Essential Serum creatinine / eGFR Required before NSAID, opioid, or gabapentinoid initiation. MBS Item 66503 (renal function test).
Essential Liver function tests (LFTs) Baseline before paracetamol (chronic use) and NSAIDs. MBS Item 66512. Assess hepatic impairment for dose adjustment.
Available Full blood count (FBC) Baseline before NSAIDs (monitoring for GI blood loss, anaemia); before opioids in hospitalised patients. MBS Item 66515.
Available Paracetamol level (plasma) Overdose assessment — Rumack-Matthew nomogram. Available in all Australian hospital laboratories within 1–2 hours.
Available INR / coagulation If patient on warfarin and commencing NSAID; NSAIDs potentiate anticoagulant effect. MBS Item 66534.
Specialist Opioid urine drug screen If substance use disorder suspected; confirm compliance or detect illicit use. Available in hospital toxicology labs.
Referral Pain medicine specialist review Refractory acute pain, complex chronic pain patients, opioid tolerance, or suspected neuropathic pain requiring specialist assessment.

Monitoring

General Monitoring Principles

  • Reassess pain severity (NRS) at defined intervals: 30 min post parenteral opioid, 60 min post oral opioid, 1–2 hours post NSAID/paracetamol.
  • Monitor vital signs — respiratory rate, oxygen saturation, sedation score (e.g., Pasero Opioid Sedation Scale) for all patients receiving opioids.
  • Document pain reassessment in the medical record as per NSQHS Clinical Governance Standard.
  • Ensure naloxone is accessible wherever opioids are administered.

Opioid-Specific Monitoring

Parameter Frequency Action Threshold
Respiratory rate Q1H for 4H post-initiation, then Q4H <10 breaths/min → withhold opioid, assess, consider naloxone
SpO₂ Continuous if IV PCA; intermittent if oral <92% → supplemental O₂, reassess analgesia plan
Sedation score Q1H for 4H, then Q4H Score ≥3 (arousable with stimulation) → withhold opioid, monitor closely
Pain score (NRS) Q4H and 30–60 min post-dose Persistent NRS ≥7 → review regimen, consider adjuvants or specialist referral
Bowel function Daily No bowel movement >3 days → commence stool softener (docusate + senna) prophylactically

NSAID Monitoring

  • Check eGFR at baseline and after 5–7 days of continued NSAID use in hospitalised patients.
  • Monitor for GI symptoms (dyspepsia, melaena, haematemesis); co-prescribe PPI in at-risk patients.
  • Check blood pressure — NSAIDs may elevate BP and antagonise antihypertensives.
  • Monitor FBC for occult GI blood loss if prolonged use (>5 days).

Special Populations

🤰 Pregnancy & Breastfeeding
Paracetamol Safe in all trimesters. First-line analgesic in pregnancy. Compatible with breastfeeding.
NSAIDs Contraindicated from 30 weeks gestation (ductus arteriosus closure, oligohydramnios). Avoid in first trimester if possible. Ibuprofen is compatible with breastfeeding (short courses).
Opioids Use at lowest dose for shortest duration. Morphine is the preferred strong opioid. Codeine — risk of neonatal respiratory depression (avoid in breastfeeding mothers who are CYP2D6 ultra-rapid metabolisers). Tramadol — limited data; avoid in third trimester.
Gabapentinoids Category B3 — avoid unless benefit outweighs risk. Limited data in pregnancy. Pregabalin excreted in breast milk.
👶 Paediatrics
Paracetamol First-line from neonatal period. 15 mg/kg Q4–6H PO; 7.5 mg/kg Q6–8H IV in neonates. Weight-based dosing is essential. Use age-appropriate formulations.
Ibuprofen From 3 months. 5–10 mg/kg TDS–QID. Avoid in dehydration, renal impairment, and varicella (increased risk of necrotising fasciitis).
Opioids Morphine 0.05–0.1 mg/kg IV Q2–4H or 0.1–0.2 mg/kg PO Q4H. Intranasal fentanyl 1.5 mcg/kg for procedural pain (ED). Codeine contraindicated <12 years (TGA).
Ketamine (procedural) 1–2 mg/kg IV or 4–5 mg/kg IM for procedural sedation and analgesia in ED. Monitor airway and have emergency equipment ready.
👴 Elderly (≥65 years)
Paracetamol First-line. Consider max 3 g/day in frail elderly with low body weight or hepatic concerns.
NSAIDs Use with extreme caution — increased risk of GI haemorrhage, AKI, cardiovascular events. If required, use lowest dose for ≤5 days with PPI. Prefer topical NSAIDs for musculoskeletal pain.
Opioids Start at 50% of standard dose. Increased sensitivity, slower clearance, falls risk, delirium. Avoid long-acting formulations. Morphine preferred; fentanyl safest in renal impairment. Monitor sedation score closely.
Gabapentinoids Start at lowest dose (gabapentin 100 mg OD; pregabalin 25 mg OD) and titrate slowly. Risk of dizziness, falls, cognitive impairment.
🫘 Renal Impairment
Paracetamol Safe — first-line. No dose adjustment unless combined with hepatic impairment. Avoid prolonged high doses in dialysis patients.
NSAIDs Avoid if eGFR <30. If eGFR 30–60: use for ≤5 days, monitor creatinine. COX-2 inhibitors carry similar renal risk.
Opioids Morphine active metabolites (M6G) accumulate — reduce dose and extend interval; avoid if eGFR <15. Fentanyl is the safest strong IV opioid in renal failure. Oxycodone — use cautiously with dose reduction. Tramadol — reduce dose 50%, extend interval.
Gabapentinoids Gabapentin requires significant dose reduction (see dosing table). Pregabalin — dose adjusted by eGFR. Both renally cleared.
🫁 Hepatic Impairment
Paracetamol Max 2 g/day in chronic liver disease or severe impairment. Increased risk of hepatotoxicity due to depleted glutathione stores.
NSAIDs Avoid in severe hepatic impairment (Child-Pugh C). Increased bleeding risk due to coagulopathy and portal hypertensive gastropathy. Use with caution in moderate impairment.
Opioids Reduce dose by 50% and extend intervals. Hepatic encephalopathy risk with all opioids. Morphine and tramadol have highest risk; fentanyl may be preferred.
🛡️ Immunocompromised
General considerations Pain may be blunted or atypical in presentation (e.g., neutropenic patients). NSAIDs may mask fever — use with caution during neutropenic episodes. Opioids may be required at higher doses in complex pain syndromes (e.g., mucositis, visceral involvement). Gabapentinoids for chemotherapy-induced peripheral neuropathy.
Drug interactions Check interactions with immunosuppressants (e.g., tacrolimus/cyclosporine with NSAIDs — nephrotoxicity potentiation). Opioids may interact with azole antifungals (CYP3A4 inhibition).

Multimodal Analgesia — Putting It All Together

Multimodal analgesia combines agents with different mechanisms to achieve superior pain control with fewer opioid-related adverse effects. This approach is endorsed by ANZCA, the ACSQHC, and is standard in Enhanced Recovery After Surgery (ERAS) programmes across Australian hospitals.

Stepwise Approach by Pain Severity

1
Mild Pain (NRS 1–3)
Paracetamol 1 g QID ± topical NSAID. Non-pharmacological measures (ice, elevation, rest, positioning). Reassess at 24–48 hours.
2
Moderate Pain (NRS 4–6)
Paracetamol 1 g QID + NSAID (e.g., ibuprofen 400 mg TDS or naproxen 500 mg BD) ± tramadol 50–100 mg PO Q4–6H PRN. Add gabapentinoid if neuropathic component. Reassess within 24 hours.
3
Severe Pain (NRS 7–10)
Paracetamol IV 1 g Q6H + NSAID (IV ketorolac 30 mg or oral) + strong opioid (morphine 2.5–5 mg IV titrated or oxycodone 10 mg PO). Add adjuvant (ketamine 0.1–0.3 mg/kg IV, dexamethasone 8 mg IV, regional block). Involve acute pain service if pain persists >48 hours.

Quick Reference — Common Acute Pain Presentations

Renal colic
IV ketorolac 30 mg + paracetamol IV; or morphine 0.1 mg/kg IV PRN
Until stone passage
NSAIDs first-line for renal colic (reduce ureteric spasm); IV fluids for hydration
Fracture (limb)
Paracetamol + ibuprofen + regional block (e.g., fascia iliaca, haematoma block); opioids PRN
2–5 days
Regional anaesthesia is opioid-sparing; splinting and ice provide additional analgesia
Post-operative (abdominal)
Paracetamol IV + ketorolac IV + TAP block ± PCA morphine ± dexamethasone 8 mg IV
24–72 hours
ERAS protocol; transition to oral as soon as tolerated; multimodal approach reduces opioid by 30–50%
Acute low back pain
Paracetamol + NSAID (naproxen or ibuprofen); muscle relaxant (diazepam 2–5 mg PRN ≤5 days) if spasm
3–7 days
Avoid opioids where possible; activity modification, physiotherapy referral; gabapentin if radicular
Dental pain
Ibuprofen 400 mg + paracetamol 1 g PO (combination superior to either alone)
3–5 days
Definitive treatment is dental intervention; opioids rarely indicated

Aboriginal and Torres Strait Islander Health Considerations

Aboriginal and Torres Strait Islander Health

Aboriginal and Torres Strait Islander Australians experience a higher burden of acute and chronic pain, higher rates of injury and hospitalisation, and greater prevalence of conditions requiring analgesia (e.g., renal disease, musculoskeletal trauma, dental caries). Culturally safe, trauma-informed pain management is essential.

Access barriers
Many Aboriginal and Torres Strait Islander people live in remote and very remote areas with limited pharmacy access and workforce shortages. PBS co-payment exemptions and Close the Gap PBS scripts support medication affordability. Ensure analgesic supply aligns with clinic visit frequency.
Health literacy and communication
Use plain language, visual aids, and interpreters when needed (English may not be a first language). Explain the purpose, dose, and duration of each analgesic clearly. Involve family and community in pain management discussions where culturally appropriate.
Opioid stewardship
Aboriginal and Torres Strait Islander communities have experienced harms related to opioid prescribing. Apply the same stewardship principles: clear indication, minimum effective dose, time-limited supply, and documented plan. Utilise real-time prescription monitoring (e.g., SafeScript, QScript) where available. Engage Aboriginal Health Workers in medication education and follow-up.
Chronic disease burden
Higher prevalence of chronic kidney disease, diabetes, and cardiovascular disease modifies analgesic choice. Avoid NSAIDs in CKD (common in this population). Prefer paracetamol and adjuvant strategies. Monitor renal function proactively.
Cultural considerations
Pain expression may differ culturally. "Sorry Business" (bereavement) and cultural obligations may affect hospital attendance and medication adherence. Ensure pain plans are flexible and culturally respectful. Recognise the role of traditional healing alongside pharmacological management and integrate where the patient wishes.
Programme support
Refer to Indigenous-specific health programmes: Aboriginal Community Controlled Health Organisations (ACCHOs), Royal Flying Doctor Service (RFDS) for remote areas, and Close the Gap pharmacy programmes for affordable medicines. The Australian Indigenous Doctors' Association (AIDA) provides resources for culturally safe prescribing.

📚 References

  1. 1. Australian and New Zealand College of Anaesthetists (ANZCA), Faculty of Pain Medicine. Acute Pain Management: Scientific Evidence. 5th ed. Melbourne: ANZCA; 2020.
  2. 2. Australian Commission on Safety and Quality in Health Care (ACSQHC). National Safety and Quality Health Service Standards. 2nd ed. Sydney: ACSQHC; 2021.
  3. 3. World Health Organization. WHO Guidelines on the Pharmacological Treatment of Persisting Pain in Children with Medical Illnesses. Geneva: WHO; 2012.
  4. 4. Schug SA, Palmer GM, Scott DA, Halliwell R, Trinca J. Acute pain management: scientific evidence, fourth edition, 2015. Anaesthesia and Intensive Care. 2015;43(6):681–695.
  5. 5. Derry S, Wiffen PJ, Moore RA, McNicol ED, Bell RF, Blyth FM, et al. Oral nonsteroidal anti-inflammatory drugs for acute postoperative pain in adults. Cochrane Database Syst Rev. 2017;(11):CD006342.
  6. 6. McNicol ED, Ferguson MC, Hudcova J. Patient controlled opioid analgesia versus non-patient controlled opioid analgesia for postoperative pain. Cochrane Database Syst Rev. 2015;(6):CD003348.
  7. 7. Therapeutic Goods Administration (TGA). Codeine information hub — changes to availability of codeine. Canberra: Australian Government Department of Health; 2018.
  8. 8. Australian Institute of Health and Welfare (AIHW). Opioid harm in Australia: and comparisons between Australia and Canada. Cat. no. HSE 210. Canberra: AIHW; 2018.
  9. 9. National Prescribing Service (NPS MedicineWise). Opioids, chronic non-cancer pain and the balance of benefits and harms. NPS Radar. Sydney: NPS MedicineWise; 2019.
  10. 10. Royal Children's Hospital Melbourne. Analgesic prescribing guidance for children. Melbourne: RCH; 2023. Available at: https://www.rch.org.au/clinicalguide/
  11. 11. Pharmaceutical Benefits Scheme (PBS). Australian Government Department of Health. PBS schedule of pharmaceutical benefits. Available at: https://www.pbs.gov.au
  12. 12. Krebs EE, Gravely A, Nugent S, Jensen AC, DeRonne B, Goldsmith ES, et al. Effect of opioid vs nonopioid medications on pain-related function in patients with chronic back pain or hip or knee osteoarthritis pain: the SPACE randomized clinical trial. JAMA. 2018;319(9):872–882.
  13. 13. Meissner W, Coluzzi F, Fletcher D, Huygen F, Morlion B, Neugebauer E, et al. Improving the management of post-operative acute pain: priorities for change. Curr Med Res Opin. 2015;31(11):2131–2143.
  14. 14. Australian Indigenous Doctors' Association (AIDA). AIDA policy statement: Closing the gap in Indigenous health outcomes. Canberra: AIDA; 2020.
for PBS scripts. Utilise ACCHS pharmacies and Remote Area Aboriginal Health Worker programs for medication supply in remote areas. Avoid initiating benzodiazepines; support holistic pain management including community-based exercise programs.
Preventive health
Promote bone health: encourage vitamin D supplementation (1000 IU daily in deficient individuals), smoking cessation support, reduction of alcohol intake, and weight-bearing exercise. MBS Item 715 health checks provide a structured opportunity to assess bone health, screen for osteoporosis risk factors, and discuss musculoskeletal health in a culturally safe context.

Quick Reference: Differential Diagnosis at a Glance

Costovertebral dysfunction
Paracetamol ± NSAID; manual therapy
2–6 weeks
Provocable on palpation; no red flags
Thoracic compression fracture
Paracetamol; ± calcitonin; DXA + osteoporosis Rx
6–12 weeks healing
Elderly; osteoporosis; acute onset
ACS (posterior MI)
Aspirin 300 mg, GTN, heparin; urgent PCI
Time-critical
ECG, troponin; CV risk factors
Aortic dissection
IV labetalol; urgent CT aortogram; surgery (Type A)
Time-critical
Tearing pain; BP differential >20 mmHg
Vertebral osteomyelitis
IV antibiotics (vancomycin + ceftriaxone initially); ID consult
6 weeks IV antibiotics
Fever, elevated CRP, IV drug use
Biliary colic / cholecystitis
Paracetamol ± morphine; lap cholecystectomy
Surgical within 72 h (cholecystitis)
RUQ/infrascapular; post-prandial; RUQ US

📚 References

  1. 1. Briggs AM, Smith AJ, Straker LM, Bragge P. Thoracic spine pain in the general population: prevalence, incidence and associated factors in children, adolescents and adults. A systematic review. BMC Musculoskelet Disord. 2009;10:77.
  2. 2. National Health and Medical Research Council (NHMRC). Evidence-based management of acute musculoskeletal pain. Canberra: NHMRC; 2003 (updated 2020).
  3. 3. Australian Institute of Health and Welfare (AIHW). Aboriginal and Torres Strait Islander Health Performance Framework: Summary report 2023. Canberra: AIHW; 2023.
  4. 4. Deyo RA, Rainville J, Kent DL. What can the history and physical examination tell us about low back pain? JAMA. 1992;268(6):760–765.
  5. 5. Stochkendahl MJ, Kjaer P, Hartvigsen J, et al. National Clinical Guidelines for non-surgical treatment of patients with recent onset low back pain or lumbar radiculopathy. Europ Spine J. 2018;27(1):60–75.
  6. 6. Erwin WM, Jackson PC, Homonko DA. Innervation of the human costovertebral joint: implications for clinical back pain syndromes. J Manipulative Physiol Ther. 2000;23(6):395–403.
  7. 7. Royal Australian College of General Practitioners (RACGP). Guidelines for preventive activities in general practice. 9th edn. Melbourne: RACGP; 2018 (updated 2023).
  8. 8. Hirsch JA, Singh V, Falco FJE, et al. Thoracic facet joint interventions. Pain Physician. 2016;19(4):E581–E593.
  9. 9. Erwin WM, Jackson PC. The costovertebral joint: anatomy, biomechanics, and clinical significance in thoracic back pain syndromes. J Can Chiropr Assoc. 2003;47(2):112–120.
  10. 10. Strayer RJ, Gunnerson JM, Brown LH, et al. Aortic dissection: clinical features, diagnosis, and management. Aust Crit Care. 2019;32(2):144–153.
  11. 11. Ombregt L. A system of orthopaedic medicine. 3rd edn. Edinburgh: Churchill Livingstone Elsevier; 2013. Chapter 18: Thoracic spine.
  12. 12. Lin CC, Chen KH, Li DM, et al. Characteristics and outcomes of patients presenting with thoracic back pain to the emergency department. Emerg Med Australas. 2020;32(5):805–811.
for PBS-listed medicines at participating pharmacies.
Cultural safety
Engagement with Aboriginal Community Controlled Health Organisations (ACCHOs) is essential. Cultural safety training for non-Indigenous clinicians, use of Aboriginal Health Workers and Liaison Officers, and incorporation of traditional healing practices alongside Western medicine improve treatment adherence and outcomes. Avoidance of eye contact, respect for gender-sensitive examination practices, and understanding of sorry business protocols are critical elements of culturally safe care.
Medication adherence
Complex DMARD regimens with frequent monitoring requirements present adherence challenges. Long-acting depot injections (e.g., methotrexate SC) may improve adherence compared to oral regimens. Community pharmacy partnerships through the Indigenous Pharmacy Programmes improve medication management.
Specific conditions
Rheumatic heart disease (RHD) requires secondary prophylaxis with benzathine penicillin G (BPG) 1.2 MU IM every 3–4 weeks for a minimum of 10 years or until age 21 (whichever is longer). RHD registers (e.g., NT RHD Register) facilitate recall and follow-up. The Australian RHD Endgame Strategy targets elimination by 2031.
Referral pathways
Referral through ACCHOs and Aboriginal Hospital Liaison Officers (AHLOs) improves engagement. The Specialist Outreach Assistance Programme provides funded specialist visits to remote communities. NT, WA, and QLD have specific rheumatology outreach programmes targeting Indigenous communities.

📚 References

  1. 1. Australian Institute of Health and Welfare (AIHW). Autoimmune disease in Australia. Cat. no. PHE 312. Canberra: AIHW; 2023.
  2. 2. Fraenkel L, Bathon JM, England BR, et al. 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care Res. 2021;73(7):924–939.
  3. 3. Fanouriakis A, Kostopoulou M, Alber K, et al. 2019 update of the EULAR recommendations for the management of systemic lupus erythematosus. Ann Rheum Dis. 2019;78(6):736–745.
  4. 4. Chung SA, Langford CA, Maz M, et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Care Res. 2021;73(11):1583–1599.
  5. 5. Smolen JS, Landewé RBM, Bijlsma JWJ, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update. Ann Rheum Dis. 2023;82(1):3–18.
  6. 6. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook. Australian Government Department of Health; 2024. Available from: immunisationhandbook.health.gov.au.
  7. 7. Rheumatic Heart Disease Australia (RHDAustralia). The 2020 Australian guideline for prevention, diagnosis, and management of acute rheumatic fever and rheumatic heart disease. 3rd ed. Darwin: Menzies School of Health Research; 2020.
  8. 8. Pharmaceutical Benefits Scheme (PBS). PBS Schedule. Australian Government Department of Health. Available from: pbs.gov.au. Accessed 2024.
  9. 9. Agarwal S, Cunnington J, Nossent J. Autoimmune disease in Indigenous Australians: a systematic review. Int J Rheum Dis. 2021;24(12):1487–1498.
  10. 10. Pisetsky DS. Antinuclear antibody testing — misunderstood or misused? Clin Immunol. 2023;255:109717.
  11. 11. Bertsias GK, Tektonidou M, Amoura Z, et al. Joint European League Against Rheumatism and European Renal Association–European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of adult and paediatric lupus nephritis. Ann Rheum Dis. 2012;71(11):1771–1782.
  12. 12. Ledingham J, Deighton C; British Society for Rheumatology Standards, Audit and Guidelines Working Group. Update on the British Society for Rheumatology guidelines for prescribing TNFα blockers in adults with rheumatoid arthritis. Rheumatology. 2005;44(2):155–158.
  13. 13. National Health and Medical Research Council (NHMRC). National statement on ethical conduct in human research. Canberra: NHMRC; 2023 (updated).
for PBS-listed medicines at participating pharmacies.
Cultural safety
Engagement with Aboriginal Community Controlled Health Organisations (ACCHOs) is essential. Cultural safety training for non-Indigenous clinicians, use of Aboriginal Health Workers and Liaison Officers, and incorporation of traditional healing practices alongside Western medicine improve treatment adherence and outcomes. Avoidance of eye contact, respect for gender-sensitive examination practices, and understanding of sorry business protocols are critical elements of culturally safe care.
Medication adherence
Complex DMARD regimens with frequent monitoring requirements present adherence challenges. Long-acting depot injections (e.g., methotrexate SC) may improve adherence compared to oral regimens. Community pharmacy partnerships through the Indigenous Pharmacy Programmes improve medication management.
Specific conditions
Rheumatic heart disease (RHD) requires secondary prophylaxis with benzathine penicillin G (BPG) 1.2 MU IM every 3–4 weeks for a minimum of 10 years or until age 21 (whichever is longer). RHD registers (e.g., NT RHD Register) facilitate recall and follow-up. The Australian RHD Endgame Strategy targets elimination by 2031.
Referral pathways
Referral through ACCHOs and Aboriginal Hospital Liaison Officers (AHLOs) improves engagement. The Specialist Outreach Assistance Programme provides funded specialist visits to remote communities. NT, WA, and QLD have specific rheumatology outreach programmes targeting Indigenous communities.

📚 References

  1. 1. Australian Institute of Health and Welfare (AIHW). Autoimmune disease in Australia. Cat. no. PHE 312. Canberra: AIHW; 2023.
  2. 2. Fraenkel L, Bathon JM, England BR, et al. 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care Res. 2021;73(7):924–939.
  3. 3. Fanouriakis A, Kostopoulou M, Alber K, et al. 2019 update of the EULAR recommendations for the management of systemic lupus erythematosus. Ann Rheum Dis. 2019;78(6):736–745.
  4. 4. Chung SA, Langford CA, Maz M, et al. 2021 American College of Rheumatology/Vasculitis Foundation guideline for the management of antineutrophil cytoplasmic antibody-associated vasculitis. Arthritis Care Res. 2021;73(11):1583–1599.
  5. 5. Smolen JS, Landewé RBM, Bijlsma JWJ, et al. EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2022 update. Ann Rheum Dis. 2023;82(1):3–18.
  6. 6. Australian Technical Advisory Group on Immunisation (ATAGI). Australian Immunisation Handbook. Australian Government Department of Health; 2024. Available from: immunisationhandbook.health.gov.au.
  7. 7. Rheumatic Heart Disease Australia (RHDAustralia). The 2020 Australian guideline for prevention, diagnosis, and management of acute rheumatic fever and rheumatic heart disease. 3rd ed. Darwin: Menzies School of Health Research; 2020.
  8. 8. Pharmaceutical Benefits Scheme (PBS). PBS Schedule. Australian Government Department of Health. Available from: pbs.gov.au. Accessed 2024.
  9. 9. Agarwal S, Cunnington J, Nossent J. Autoimmune disease in Indigenous Australians: a systematic review. Int J Rheum Dis. 2021;24(12):1487–1498.
  10. 10. Pisetsky DS. Antinuclear antibody testing — misunderstood or misused? Clin Immunol. 2023;255:109717.
  11. 11. Bertsias GK, Tektonidou M, Amoura Z, et al. Joint European League Against Rheumatism and European Renal Association–European Dialysis and Transplant Association (EULAR/ERA-EDTA) recommendations for the management of adult and paediatric lupus nephritis. Ann Rheum Dis. 2012;71(11):1771–1782.
  12. 12. Ledingham J, Deighton C; British Society for Rheumatology Standards, Audit and Guidelines Working Group. Update on the British Society for Rheumatology guidelines for prescribing TNFα blockers in adults with rheumatoid arthritis. Rheumatology. 2005;44(2):155–158.
  13. 13. National Health and Medical Research Council (NHMRC). National statement on ethical conduct in human research. Canberra: NHMRC; 2023 (updated).