6 General adult psychiatry6.3 Liaison psychiatry
6.3 Pain: psychiatric aspects and management
2 min read1 figure
Written by Resident Doctor Committee · Published
Types of pain
Pain is an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Sensory nerve activity alone (nociception) does not establish it.
Chronic pain persists or recurs for over three months.
Chronic primary pain is a condition in itself, whereas secondary pain is adequately explained by another disease or lesion.
Mechanism | Cause | Example |
|---|---|---|
Nociceptive | Tissue damage activates nociceptors | Fracture, osteoarthritis |
Neuropathic | Disease or lesion of the somatosensory system | Diabetic neuropathy, post-herpetic neuralgia |
Nociplastic | Altered pain processing without enough damage or lesion to explain it | Fibromyalgia |
Psychiatric comorbidity
Depression affects about 40% of pain clinic patients, and pain and depression reinforce each other through sleep loss and inactivity.
Suicide risk rises with chronic pain beyond its link with depression, so ask about hopelessness, plans and access to analgesics.
Duloxetine and amitriptyline can relieve pain without depression, through descending serotonergic and noradrenergic pathways.
Managing chronic primary pain
The National Institute for Health and Care Excellence (NICE) guideline NG193 recommends supervised group exercise and either cognitive behavioural therapy or acceptance and commitment therapy.
Antidepressants to consider in adults are amitriptyline, citalopram, duloxetine, fluoxetine, paroxetine or sertraline.
Do not start opioids, non-steroidal anti-inflammatory drugs, paracetamol, benzodiazepines, antipsychotics, gabapentinoids or ketamine.
For neuropathic pain, NICE offers amitriptyline, duloxetine, gabapentin or pregabalin first, with carbamazepine for trigeminal neuralgia.
Antidepressants in palliative care
Antidepressants are roughly equal in efficacy for mood, so side effects and secondary benefits decide the choice.
Drug | Chosen when |
|---|---|
Duloxetine | Pain, especially neuropathic, coexists, because it treats both |
Selective serotonin reuptake inhibitors | Tolerability matters most |
Mirtazapine | Sleep and appetite are poor |
Methylphenidate | Prognosis is very short |
Tricyclics | Analgesia is wanted, at the cost of poor tolerability |
Opioids
Term | Meaning |
|---|---|
Tolerance | Same dose gives less effect; not proof of addiction |
Physical dependence | Withdrawal on abrupt stopping; arises with appropriate prescribing |
Opioid use disorder | Craving, impaired control and continued use despite harm |
Opioid-induced hyperalgesia | Increased, often diffuse pain sensitivity that may improve with gradual reduction |
Doses above 50 mg oral morphine equivalent daily raise risk substantially, and doses above 90 mg need specialist advice.
Combining opioids with benzodiazepines, gabapentinoids or alcohol increases respiratory depression.
Taper slowly, because lost tolerance makes returning to a previous dose dangerous.