Opioids (Endone, OxyContin, Tramal, Norspan, Suboxone) — patient guide

Opioids act on the mu-opioid receptors in the brain, spinal cord, and (importantly for side effects) the gut. Mu-receptor activation in the brain produces analgesia by reducing the perception of pain and the emotional response to it. Mu-receptor activation in the gut slows peristalsis (the wave of contraction that moves food along) — which is why opioid-induced constipation is universal and dose-dependent. Mu-receptor activation in the brainstem reduces the respiratory drive — which is why opioid overdose causes slow or shallow breathing and is the mechanism of opioid-related death.

Full mu-agonists (morphine, oxycodone, hydromorphone, fentanyl, methadone) produce a dose-dependent maximum effect — more drug produces more effect (and more respiratory depression) without a ceiling.

Partial mu-agonists (buprenorphine — Norspan patch, Suboxone, Sublocade, Buvidal) have a ceiling — more drug above a certain dose does not produce more effect. This reduces single-agent respiratory depression compared with full agonists but does NOT protect against fatal combination with benzodiazepines, Z-drugs, gabapentinoids, or alcohol.

Atypical opioids (tramadol, tapentadol) have a weak mu-agonist effect combined with reuptake inhibition of neurotransmitters (tramadol — serotonin and noradrenaline; tapentadol — noradrenaline only). The dual mechanism gives extra analgesic effect at neuropathic-pain pathways but adds distinctive risks — tramadol particularly carries serotonin syndrome and seizure risk.

Pro-drugs (codeine) are largely inactive until metabolised. Codeine is converted to morphine by the CYP2D6 liver enzyme. CYP2D6 genetic variation produces a wide range of effective doses — around 7-10% of Caucasian Australians are ultra-rapid metabolisers (codeine converts faster and more completely to morphine, with overdose-relevant peaks), and around 7% are poor metabolisers (codeine produces little to no analgesia).

Common — usually settle in 1-2 weeks

• Sedation, drowsiness, slowed reflexes — common in the first week and after every dose increase. Do not drive or operate machinery until you know how the medicine affects you.
• Nausea and vomiting — common in the first 1-2 weeks; usually settle. Antiemetic cover for the first 1-2 weeks is reasonable; ondansetron plus tramadol combination raises serotonin syndrome risk and is best avoided.
• Itching, flushing — particularly with morphine (histamine release). Usually settles or persists but does not signal harm.
• Dry mouth — common; persistent; the mechanism behind opioid-related dental caries.
• Headache, mild dizziness — usually settle within the first week.

Common — does NOT settle

• Opioid-induced constipation — universal, dose-dependent, persistent for the entire duration of opioid therapy. Prophylactic combination osmotic plus stimulant laxative from day 1.

Common — develops over weeks to months

• Tolerance to analgesic effect — the same dose gives less benefit over time. Dose escalation does not reliably restore the lost effect.
• Physical dependence — the body adapts; abrupt cessation causes withdrawal syndrome.
• Opioid-induced hyperalgesia — paradoxical worsening of pain on chronic opioid therapy. Mechanism is central sensitisation of pain-processing pathways. The defensible response is a planned, supervised taper rather than dose escalation.
• Hypogonadism — chronic opioid therapy suppresses the hormone axis. Low testosterone, low oestradiol, fatigue, low libido, erectile dysfunction, menstrual irregularity, mood disturbance, reduced muscle mass, reduced bone density. Often missed because attributed to the underlying pain. Annual hormone screen reasonable.
• Sleep apnoea unmasking — opioids depress the arousal response. Combination of opioid plus untreated sleep apnoea plus another sedating medicine is a documented AU overdose-death pattern.
• Dental caries — secondary to xerostomia. Annual dental review reasonable.

Uncommon

• Mood disturbance, depression, anxiety — both lifts and dips reported.
• Reduced libido and sexual dysfunction — usually mediated by hypogonadism.
• Sweating, hot flushes — variable.
• Urinary retention — particularly in older men with prostatic enlargement.

Rare but serious — act quickly

• Respiratory depression — slow or shallow breathing, blue lips, hard to rouse, unresponsive. Particularly after a combined dose with a benzodiazepine, Z-drug, gabapentinoid, sedating antidepressant, sedating antihistamine, or alcohol. Call 000 immediately. Give take-home naloxone (Nyxoid intranasal or Prenoxad injectable) if available.
• Anaphylaxis — sudden swelling of face, lips, tongue, or throat; widespread hives; respiratory distress. Call 000.
• Serotonin syndrome (tramadol specifically) — agitation, confusion, hyperreflexia, clonus (involuntary muscle jerks), autonomic instability (sweating, fast heart rate, fluctuating blood pressure), hyperthermia. Stop the tramadol and seek urgent medical care.
• Severe skin reaction (Stevens-Johnson syndrome with codeine or tramadol — rare) — widespread rash, blistering, peeling, or rash with fever. Stop the medicine and seek urgent care.
• Seizure (tramadol specifically at high doses or in combination with other seizure-threshold-lowering agents) — stop and seek urgent care.
• New or worsening thoughts of suicide or self-harm — tell your GP immediately or contact Lifeline 13 11 14. Call 000 if safety is at risk right now.

The combination warning above is the most important interaction conversation for this class. This section covers the rest.

Tramadol-specific — serotonin syndrome and seizure. Tramadol is metabolised by CYP2D6 (same as codeine — same ultra-rapid metaboliser and poor metaboliser variability). Serotonin syndrome risk in combination with serotonergic agents — SSRIs (citalopram, escitalopram, sertraline, paroxetine, fluoxetine, fluvoxamine), SNRIs (venlafaxine, duloxetine, desvenlafaxine), tricyclics (amitriptyline, nortriptyline, dosulepin, clomipramine), MAOIs, fentanyl, ondansetron, linezolid, methylene blue, St John’s wort, MDMA. Flag every patient combining tramadol with an antidepressant. Seizure risk — avoid in epilepsy and in people on other seizure-threshold-lowering medicines.

Methadone-specific — QT interval prolongation. Combination with antiarrhythmics (amiodarone, sotalol, quinidine), macrolide antibiotics (clarithromycin, erythromycin), fluoroquinolone antibiotics (moxifloxacin, ciprofloxacin), azole antifungals, antipsychotics (haloperidol, droperidol, quetiapine at high dose), or antiemetics (ondansetron, domperidone) can produce additive QT prolongation with risk of torsade de pointes. Baseline and follow-up ECG. Coordinated with the specialist methadone prescriber.

Fentanyl-specific — CYP3A4. Fentanyl is a CYP3A4 substrate. Strong CYP3A4 inhibitors raise fentanyl levels with overdose risk — azole antifungals (fluconazole, itraconazole, voriconazole, ketoconazole), macrolide antibiotics (clarithromycin, erythromycin), protease inhibitors (ritonavir), grapefruit juice in large quantities. Strong CYP3A4 inducers lower fentanyl levels with risk of withdrawal symptoms and inadequate analgesia — rifampicin, carbamazepine, phenytoin, St John’s wort. Tell your GP and pharmacist about every new prescription, including short antibiotic courses.

Methadone — same CYP3A4 considerations as fentanyl.

Codeine-specific — CYP2D6 ultra-rapid metaboliser warning. Particularly relevant in breastfeeding mothers (infant fatalities have been reported via breast milk transfer) and children under 12 (TGA and FDA boxed warnings after fatal post-tonsillectomy overdoses in ultra-rapid metaboliser children).

Naltrexone (specifically) — never combine with an active opioid. Naltrexone precipitates withdrawal in opioid-dependent patients. The gap between opioid cessation and naltrexone initiation is typically 7-10 days. Naloxone in Targin (oxycodone plus naloxone fixed combination) is low systemic absorption and does NOT precipitate withdrawal in established users; naloxone in Suboxone is included to deter intravenous misuse and is not absorbed sublingually in clinically meaningful amounts.

Warfarin — variable effect on INR; monitor closely when an opioid is added, removed, or dose-changed.

Peri-operative general anaesthetics, propofol, ketamine, dexmedetomidine — additive sedation and respiratory depression. The anaesthetist needs to know every opioid and every combination-risk medicine you are taking.

Food. No specific food restrictions for most opioids. The fentanyl patch and Norspan patch are not affected by food. Methadone is not affected by food. Liquid morphine (Ordine) has some absorption variability with food but is usually clinically minor.

Alcohol. Avoid entirely on opioid therapy. Additive sedation, additive respiratory depression, additive overdose risk. The ‘one or two drinks with dinner’ habit becomes much higher risk when combined with any opioid.

Generic substitution at the pharmacy. Generic opioids are bioequivalent to brand-name versions at PBS pricing. If the pharmacist offers a generic, it is fine to take.

Opioid therapy requires ongoing clinical monitoring rather than routine blood-test monitoring in most cases.

• Pain and function — at every review. Pain score (0-10) and function (what can you do that you could not before, or what can you no longer do that you used to do).
• Side effects — sedation, constipation, nausea, dental health, sleep, mood.
• Mood and suicidality screen — at every review.
• Combination-risk medicines — every prescription, every over-the-counter purchase, every supplement. Tell your GP about every new addition.
• Real-time prescription monitoring (RTPM) check — your prescriber may run a SafeScript or equivalent check at any consult. This is routine, not a sign of suspicion.
• Oral morphine equivalent daily dose (oMEDD) — your prescriber calculates this at each review. The ANZCA Faculty of Pain Medicine Opioid Calculator is the standard AU tool.

Annual reviews on long-term opioid therapy:

• Hormone screen — testosterone (men and post-menopausal women), oestradiol (pre-menopausal women), LH, FSH. If low, consider whether the symptoms (fatigue, low libido, mood disturbance) are at least partly hormone-mediated rather than purely pain-related.
• Dental review — caries risk is elevated.
• Sleep study — if snoring, witnessed pauses, unrefreshing sleep, or daytime sleepiness.
• Renal function — particularly for morphine (active metabolite accumulates in renal impairment).
• ECG — methadone particularly (QT-interval check at baseline and at dose increases above approximately 100 mg/day or with new QT-prolonging medicines).

Tell your GP if you start any new medicine, notice a change in mood, have a near-miss with sedation or breathing, notice persistent constipation that laxatives are not solving, or notice escalating pain despite stable opioid dose (the last is the signal for opioid-induced hyperalgesia and a planned taper conversation).

Never stop an opioid suddenly after more than 2-4 weeks of regular use. The opioid withdrawal syndrome includes anxiety, restlessness, sweating, runny nose, watery eyes, dilated pupils, muscle aches, abdominal cramps, diarrhoea, fast heart rate. Withdrawal is unpleasant but not life-threatening in healthy adults — the supervised taper is the safe and humane pathway.

A typical supervised taper:

• Short-term users (under 2 weeks) — usually can stop without a formal taper.
• Established users (more than 2-4 weeks of regular use) — reduce the daily dose by approximately 10% every 1-4 weeks. Slower for higher doses. Slower for longer durations of use. Slower in people with a history of withdrawal difficulty.
• People on high-dose long-term opioids — taper may take many months. Specialist or experienced GP supervision; some patients are managed via OAT (Suboxone) as a bridge.

Rebound pain in the first 2-4 weeks is expected and is the body re-calibrating without the opioid — it is NOT the original pain returning permanently. Plan the taper around a low-stress period.

Run the non-opioid pain plan in parallel from day 1 of the taper, not at the end. Graded exercise, physiotherapy, CBT for chronic pain, ACT, mindfulness-based stress reduction, sleep optimisation, nutrient adequacy, treatment of any coexisting depression or anxiety, treatment of sleep apnoea if present.

The taper conversation typically covers: which dose drops are made when, what to expect during each drop, when to slow down or pause, what the non-opioid pain plan looks like, and what the contingency plan is if rebound pain or withdrawal symptoms become marked.

This is a planned conversation, not an improvised one. Book a dedicated review with your GP before changing the dose.

Resources for the taper journey — NPS MedicineWise: Opioids tapering and switching, the ANZCA Faculty of Pain Medicine taper resources, and the RACGP Part C Opioids resource.

Opioid-induced constipation is universal, dose-dependent, and does NOT improve with time. Unlike most opioid side effects (nausea, drowsiness — these usually settle in 1-2 weeks), opioid-induced constipation persists for the entire duration of opioid therapy.

Prophylactic laxative regimen from day 1, not as needed.

• Osmotic laxative — macrogol (Movicol, OsmoLax) one to two sachets daily; OR lactulose 15-30 mL once or twice daily.
• PLUS stimulant laxative — sennosides (Senokot) two to four tablets at night; OR bisacodyl (Dulcolax) 5-10 mg at night.

The combination of osmotic + stimulant is the standard approach. Osmotic alone is often inadequate; stimulant alone can cause cramping.

Other measures:

• Adequate fluid — 1.5 to 2 litres/day for most adults.
• Adequate fibre — 25-30 g/day from food where possible (vegetables, fruit, legumes, whole grains, nuts, seeds).
• Movement — even gentle daily walking helps gut motility.
• Magnesium oxide — useful adjunct, mild osmotic effect.

If laxatives are inadequate — speak to your GP. Second-line peripheral mu-antagonist agents (naloxegol, methylnaltrexone) work specifically on the gut without reversing the opioid effect at the brain. These are PBS-restricted; specialist guidance.

Targin (oxycodone + naloxone fixed combination) reduces opioid-induced constipation without compromising analgesia and is a reasonable consideration if the constipation is the dominant problem on oxycodone.

Do NOT ignore opioid-induced constipation — untreated, it causes faecal impaction, bowel obstruction, and emergency department presentations.

Chronic opioid therapy suppresses the hypothalamic-pituitary-gonadal (HPG) axis. Testosterone and oestradiol fall. The clinical picture — fatigue, low libido, erectile dysfunction in men, menstrual irregularity or amenorrhoea in women, mood disturbance, reduced muscle mass, reduced bone density — is often missed because the symptoms are attributed to the underlying pain or to age.

Annual hormone screen is reasonable in patients on long-term opioid therapy:

• Men — total testosterone (morning sample), LH, FSH, prolactin, SHBG. Calculate free testosterone if total is borderline.
• Pre-menopausal women — menstrual history, LH, FSH, oestradiol, prolactin.
• Post-menopausal women — symptom-based; baseline LH, FSH, oestradiol.

If hormone levels are low and symptoms are present, the conversation is whether the opioid can be tapered (which often partially restores HPG axis function over months) or whether hormone replacement is appropriate. Hormone replacement on long-term opioid therapy is specialist-led — endocrinologist input is the usual pathway.

Bone density assessment (DEXA scan) is reasonable in people on long-term opioids with low sex hormones, particularly in women under 50 with amenorrhoea and in men with low testosterone.

On an opioid and pregnant. Contact your GP and obstetric team as soon as possible. Do NOT stop the opioid abruptly — sudden cessation in pregnancy precipitates maternal withdrawal and raises fetal distress and miscarriage risk.

Neonatal abstinence syndrome (NAS). Chronic maternal opioid therapy can cause NAS after birth — the baby is exposed in utero, then withdraws after delivery. NAS is treatable; planned NICU monitoring and weaning is standard. Severity depends on maternal opioid dose, type, and timing relative to delivery.

The decision in pregnancy is whether:

• The opioid is essential (for example continuing OAT through pregnancy improves outcomes compared with attempts at abstinence in pregnancy).
• To switch agents (buprenorphine has more pregnancy safety data than methadone in some contexts).
• To taper (planned, slow, with obstetric coordination — usually deferred to the second trimester to reduce miscarriage risk).

Breastfeeding. Most opioids transfer into breast milk in small amounts. Codeine specifically is generally avoided in breastfeeding mothers — fatal infant overdoses have been reported via breast milk transfer in CYP2D6 ultra-rapid metaboliser mothers. Buprenorphine and methadone in OAT contexts are generally compatible with breastfeeding under monitoring; benefits to maternal-infant attachment and stable maternal opioid balance usually outweigh the small transfer risk.

Planning a pregnancy on chronic opioid therapy — tell your GP and obstetric team before trying. For some indications a planned taper and transition to non-opioid analgesia is appropriate before conception. For others the decision is more complex and made together with your team.

Opioid prescribing in children is specialist-only. This page does not cover paediatric opioid prescribing.

Codeine specifically is contraindicated in children under 12 years — TGA and FDA boxed warnings followed fatal post-tonsillectomy overdoses in ultra-rapid metaboliser children. Codeine is also contraindicated in children under 18 who are at increased risk of obstructive sleep apnoea (recent tonsillectomy or adenoidectomy for sleep apnoea).

If a child has a Schedule 8 opioid prescription, the prescriber is a specialist (paediatrician, paediatric oncologist, paediatric palliative care) and the supervision plan is theirs.

The Austroads Assessing Fitness to Drive standards apply.

Stable, established opioid users on a steady dose may drive after a stability period (typically 2-4 weeks after dose stable, no side effects affecting driving).

Do NOT drive:

• In the first 2-4 weeks of any opioid (start or dose change).
• On the same day as combination with another sedating medicine (benzodiazepine, Z-drug, gabapentinoid, sedating antihistamine, sedating antidepressant).
• After alcohol on opioid therapy at all.
• If you feel sedated, dizzy, or unsteady.

Heavy goods vehicles, public passenger vehicles, and rail safety roles have stricter conditional standards. Your prescriber may need to notify the licensing authority.

If unsure, ask before driving rather than after a near-miss. The defensible practice is to err on the side of not driving; the medico-legal and personal cost of a sedation-related crash is severe.

The fentanyl patch (Durogesic, Denpax) deserves a separate section. Two safety issues specific to the patch:

Heat exposure accelerates patch release. Heating pads, fever, sauna, hot bath, hot car dashboard — all have caused fatal overdoses by accelerating the rate of fentanyl absorption from the patch. Counsel rigorously against heat exposure when a patch is on. If you develop a fever, tell your GP.

Used patches retain enough fentanyl to be lethal. Fold the patch sticky-side to sticky-side immediately on removal and dispose in a sealed container (then in the bin). Child and pet exposure to discarded patches has caused AU fatalities. Some pharmacies accept used patches for safe disposal — ask.

Other fentanyl patch rules:

• Apply to clean, dry, intact skin on the upper arm, upper back, or upper chest. Rotate sites — same site no more often than every 21 days.
• Steady plasma levels are reached over 12-24 hours after first patch.
• Residual fentanyl effect persists 12-24 hours after patch removal.
• Never cut or alter the patch.
• Never initiate fentanyl patch in an opioid-naive patient — this is a documented AU coroner-case overdose pattern.

Have take-home naloxone in the home if you are on a fentanyl patch.

This is one of the most under-recognised safety conversations in chronic opioid prescribing.

If you snore loudly, have witnessed pauses in breathing, or feel unrefreshed despite adequate sleep time, ask your GP about a sleep study. Opioids depress the arousal response and worsen oxygen drops in untreated obstructive sleep apnoea. The combination of opioid plus untreated sleep apnoea plus another sedating medicine (benzodiazepine, Z-drug, alcohol) is a documented AU overdose-death pattern.

The fix is two-fold (see HealthDirect opioid medicines overview and the Better Health Channel pain management resources for plain-English background):

1. Investigate the sleep apnoea (typically a home-based recording overnight).
2. Treat it — CPAP, mandibular advancement device, weight loss, positional therapy. AND reassess the opioid dose with the prescriber.

CPAP optimisation reduces the opioid-related respiratory-depression risk meaningfully. People on long-standing opioid scripts not infrequently turn out to have undiagnosed or under-treated sleep apnoea as a major contributor to the overall risk picture.

Do NOT add a Z-drug or benzodiazepine to an existing opioid for sleep — the combination is the dominant AU overdose-death pattern.

Chronic opioid use causes xerostomia (dry mouth). Reduced saliva flow strips out the natural buffering and remineralisation that protects teeth. People on long-term opioids have higher rates of dental caries and periodontal disease.

Mitigations:

• Annual dental review.
• Saliva-replacement products (Biotene, Oral7).
• Sugar-free gum to stimulate saliva.
• Fluoride toothpaste (and sometimes higher-strength prescription fluoride toothpaste under dental supervision).
• Avoidance of frequent sugary intake — the frequency matters more than the total amount.

Tell every dentist and every dental visit what you are taking. Post-extraction analgesia planning is best coordinated with your usual prescriber; opioids do not stack safely on top of an existing opioid script.

Opioids are diverted, stolen, and accidentally accessed in Australian homes. Several safety practices reduce that risk.

• Store the medicine out of easy reach. Not on the kitchen counter, not in a handbag left on a hall table, not in the bathroom cabinet a visiting child or housemate can access.
• Use a lockable container or lockable drawer if there is any risk of unauthorised access.
• Do not share your script. An opioid handed to a friend “for their pain” can sedate, cause respiratory depression, and — particularly in combination with alcohol or another sedating medicine — kill.
• If a tablet, patch, or syringe goes missing, tell your GP. It is a brief, non-judgemental conversation and is the right thing to do.
• If you have a young child in the home or visiting, child-resistant containers are mandatory — and high-potency products (fentanyl patches, methadone liquid, hydromorphone) need extra care.
• Dispose of used fentanyl patches immediately — fold sticky-side to sticky-side and place in a sealed container.
• Return unused opioids to the pharmacy — most pharmacies accept unused medicines for safe disposal under the Return Unwanted Medicines (RUM) scheme.

From 1 January 2026, the PBS co-payment is:

• General patient — up to $25.00 per script.
• Concession card holder — up to $7.70 per script.

Authority requirements:

• Codeine, tramadol, oxycodone IR (Endone), morphine IR — PBS-listed without authority restrictions for most indications.
• Tapentadol (Palexia IR + SR) — PBS Authority required.
• Oxycodone SR (OxyContin), morphine SR (MS Contin, Kapanol), hydromorphone (Dilaudid, Jurnista) — PBS Authority required for chronic severe pain.
• Buprenorphine patch (Norspan) — PBS Authority required for chronic severe disabling pain.
• Fentanyl patch (Durogesic, Denpax) — PBS Authority required for chronic severe pain in opioid-tolerant patients.
• Methadone, buprenorphine OAT (Suboxone, Sublocade, Buvidal) — funded through the AU Opioid Dependence Treatment programme, not standard PBS.

Generic versions cost the same as brand-name versions at PBS pricing and work the same. Confirm with your pharmacist — they can show you the exact price for your script and tell you the cheapest option.

(MBS / PBS items verified 2026-05-25 via WebSearch — workspace egress to mbsonline.gov.au + pbs.gov.au still blocked; spot-check confirms current.)