Workers Compensation
Secondary psychological injury is the most expensive development on a physical injury claim. Some of it is a genuine psychiatric consequence of pain, loss and disruption. Some of it is pharmacological, caused or amplified by the opioids, sedatives and gabapentinoids the claim is already funding, and it responds to dose reduction rather than years of psychiatric treatment. Telling the two apart is a liability decision as much as a clinical one.
Why does this matter more than any other medication question on a claim?
In NSW, psychological injury claims are 12 per cent of workers compensation claims and 38 per cent of cost, with an average claim cost of $288,542 in 2024-25, up from $146,000 five years earlier. Only about half of psychological injury claimants return to work within a year, against 95 per cent for physical injury. A secondary psychological injury added to a physical claim imports those numbers into a claim that was previously tracking as a physical recovery. If the psychological symptoms are drug-induced, the claim has just acquired the cost profile of a psychiatric injury to treat something that a supervised dose reduction might have resolved in weeks.
The 2026 NSW reforms raised the whole person impairment threshold for psychological injury to 25 per cent and restructured how primary psychological claims are accepted, but secondary psychological conditions arising from a physical injury and its treatment remain a live pathway. That makes the question of what caused the symptoms more important, not less.
Which medications cause psychological symptoms?
The drugs most often funded on injury claims are among the best-documented pharmacological causes of depression, anxiety and cognitive change. Product information and the pharmacovigilance literature are consistent on the following.
| Medication class | Psychological effects documented | Typical timing on a claim |
|---|---|---|
| Opioids (oxycodone, tapentadol, tramadol, buprenorphine, morphine) | Low mood, anhedonia, emotional blunting, apathy; anxiety and dysphoria in interdose withdrawal; hypogonadism-related depression with long-term use | Emerges as use extends beyond 90 days and dose escalates; worsens with each escalation |
| Benzodiazepines (diazepam, temazepam, alprazolam) | Depression with chronic use; rebound and interdose anxiety, panic, irritability, insomnia; cognitive impairment; disinhibition | Interdose symptoms within weeks of regular use; depression and cognitive effects with months of use |
| Gabapentinoids (pregabalin, gabapentin) | Depressed mood, suicidal ideation (a regulatory warning in the antiepileptic class), euphoria followed by dysphoria, cognitive slowing, derealisation | Dose-related; often appears as dose is titrated for pain |
| Corticosteroids (prednisolone, epidural or joint injections in large or repeated doses) | Mood elevation then depression, anxiety, insomnia, irritability; rarely psychosis | Days to weeks after a course or a series of injections |
| Sedating antidepressants started for sleep (mirtazapine, amitriptyline) | Daytime sedation and emotional flattening read as worsening depression; anticholinergic cognitive effects | Weeks after initiation |
| SSRIs and SNRIs on initiation or dose change | Activation, agitation, anxiety, insomnia in the first weeks; emotional blunting; discontinuation symptoms read as relapse | First two to four weeks after start or increase; on missed doses or abrupt cessation |
| Beta-blockers, varenicline, isotretinoin, some antihypertensives | Fatigue and low mood; varenicline and isotretinoin carry specific neuropsychiatric warnings | Weeks after initiation |
The Monash group reported in the British Journal of Clinical Pharmacology in 2026 that antidepressant, benzodiazepine and gabapentinoid dispensing all rise after an Australian worker's back or neck claim begins. Read against the table, that means the psychotropic response to psychological symptoms on a claim is frequently being layered onto the drugs that may be producing them.
How is drug-induced mood change distinguished from a secondary psychiatric injury?
The same causality questions apply as for any adverse effect, with three features that are particularly telling for psychological symptoms.
The first is timing against dose. A secondary depressive disorder driven by pain and loss tends to track the injury course: it deepens with failed treatment, lost work and financial strain. A drug-induced mood change tracks the medication: it steps down with each dose increase and, critically, lifts with reduction. If the chronology shows mood declining in step with opioid or gabapentinoid escalation, the drug is the leading hypothesis.
The second is the character of the symptoms. Opioid and benzodiazepine effects are typically apathy, flattening, sedation and interdose anxiety rather than the guilt, worthlessness and ruminative content of a primary depressive episode. Gabapentinoid effects often include derealisation and cognitive fog. Steroid effects are labile and time-limited. A psychiatrist looking for these features will find them; one who has not been told the medication history will not look.
The third is dechallenge. A supervised reduction of the suspected drug, with mood monitored on a validated scale over four to eight weeks, is the single most informative investigation available and is almost never done before the psychiatric diagnosis is entered on the claim. The five-question framework is set out in full in the pillar guide on side effects versus new diagnoses.
What does this mean for liability?
Whether a secondary condition is compensable turns on whether it arose from the injury or its treatment. A drug-induced depression caused by medication prescribed for a compensable injury is, in most schemes, still a consequence of the injury. The liability question is therefore not usually whether the insurer is on risk for the symptoms, but what treatment for them is reasonably necessary and for how long. That is where the distinction bites. If the symptoms are pharmacological, the reasonably necessary treatment is a supervised dose reduction, not an open-ended psychiatric treatment plan, and the expected duration is months rather than years. If the symptoms are a primary psychiatric injury, the treatment plan and the duration are different and so is the reserve. Accepting a secondary psychological injury without first establishing which of these it is means the insurer takes on the cost profile of the worse case by default.
There is a second liability exposure that runs the other way. If a claimant's mood is being treated with an antidepressant while an escalating opioid continues to drive it, and the claimant deteriorates, the file will show that the medication cause was visible and not acted on. Insurers cannot direct prescribing, but they can document that the question was asked and that an independent review was offered.
What should a claims manager do when psychological symptoms appear?
Before accepting a secondary psychological injury or funding a psychiatric treatment plan, obtain the medication chronology and place mood onset against it. If an opioid, benzodiazepine, gabapentinoid, corticosteroid or sedating antidepressant preceded or escalated alongside the symptoms, ask the treating practitioner in writing whether medication has been considered as a cause. Ensure any psychiatric or psychological assessment is given the full medication history and asked to comment on it. Where the regimen is complex or the practitioner disagrees, refer for an independent clinical pharmacy review, which will assess causality, quantify sedative load and recommend a reduction sequence. The wider mechanism, and the other symptoms that travel with it, are covered in the article on prescribing cascades in personal injury claims and the drug-by-drug reference on side effects mistaken for new conditions.
Key Takeaways
- Secondary psychological injury is the most expensive development on a physical claim: in NSW, 12 per cent of claims, 38 per cent of cost, average $288,542.
- Opioids, benzodiazepines, gabapentinoids, corticosteroids and sedating antidepressants all cause depression, anxiety or cognitive change, and dispensing of all of them rises after a claim begins.
- Drug-induced mood change tracks dose, presents as apathy, flattening and interdose anxiety rather than ruminative depression, and lifts on reduction.
- A supervised dose reduction with mood monitored over four to eight weeks is the most informative investigation and is almost never done before the psychiatric diagnosis is entered.
- The liability question is usually not whether the insurer is on risk but what treatment is reasonably necessary: a reduction over months, or psychiatric treatment over years.
- Give every psychiatric assessor the full medication history and ask them to comment on it, and refer for pharmacist review before accepting the secondary condition.
Frequently Asked Questions
Can opioids cause depression?
Yes. Long-term opioid use is associated with new-onset depression, emotional blunting and apathy, with risk rising with duration and dose. Opioids also suppress testosterone, which contributes to low mood and fatigue in men and women. Symptoms typically improve when the dose is reduced, which distinguishes them from a primary depressive disorder.
Is a drug-induced psychological condition still compensable?
In most Australian schemes a condition caused by treatment for a compensable injury is itself a consequence of that injury. The practical question is what treatment is reasonably necessary. For a pharmacological cause that is a supervised dose reduction, not an open-ended psychiatric treatment plan, and the expected duration and cost are very different.
What is interdose withdrawal and why is it mistaken for anxiety?
Short-acting opioids and benzodiazepines taken on a schedule produce a trough before each dose in which anxiety, sweating, irritability and pain spike. Patients and prescribers read the trough as the underlying anxiety or pain breaking through and respond with a higher or more frequent dose, which deepens the next trough. The pattern is recognisable because symptoms are worst before the next dose is due.
Should a psychiatrist be told the full medication list?
Always, and asked to comment on it. A psychiatric assessment that does not address whether the presentation could be pharmacological is incomplete, and on a claim it is the difference between a diagnosis that supports a reduction plan and one that locks in years of treatment.
Primary sources: NSW workers compensation reform data and SIRA psychological injury guidance, 2026; Tefera et al, psychotropic medicine utilisation in Australian workers with compensation claims, British Journal of Clinical Pharmacology 2026; Di Donato et al, CNS Drugs 2025; TGA-approved product information for opioids, benzodiazepines, gabapentinoids and corticosteroids; Kalisch et al, Australian Prescriber 2011; Rochon and Gurwitz, Lancet 2017.
