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What is an opioid and opioid induced hyperalgesia (OIH)?

While opioids are powerful pain relievers, prolonged use can alter the body’s pain pathways and, paradoxically, increase pain sensitivity.

Opioids are a class of medications used to relieve moderate to severe pain by binding to specific receptors in the nervous system and other parts of the body. Common examples include morphine, oxycodone, and codeine. When used appropriately, opioids can be effective for short-term pain relief; however, long-term use can lead to dependence and a range of side effects that may complicate recovery.

Opioid-induced hyperalgesia (OIH) is a condition where prolonged or high-dose opioid use paradoxically increases pain sensitivity rather than relieving it. This paradox leaves patients stuck in a cycle of worsening pain and increasing medication use — often without clear recognition that opioids may be part of the problem.

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What causes opioid-induced hyperalgesia (OIH)?

When opioid use paradoxically amplifies pain sensitivity, creating a cycle where more medication leads to greater discomfort

OIH occurs when opioids alter pain pathways, lowering pain thresholds and heightening sensitivity. Neural systems become sensitised (central sensitisation), resulting in increased pain despite escalating doses.

OIH risk increases with high-dose or long-term opioid use, particularly with potent opioids like morphine, oxycodone and fentanyl. Genetic predisposition, rapid dose escalation, concurrent NMDA receptor activation, sleep deprivation, and underlying pain sensitisation further amplify risk. Patients with chronic pain or psychological stress are also more susceptible.

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Common features of opioid-induced hyperalgesia (OIH)

Distinguishing OIH from tolerance or disease progression can be difficult.

OIH can often mimic worsening of the original pain condition. However, certain patterns can suggest that opioids may be amplifying, rather than relieving, pain:

  • Pain that becomes more diffuse or spreads beyond the original site of injury or illness
  • Increased pain sensitivity despite escalating opioid doses
  • Pain that feels sharper, more intense, more constant or different in character than before
  • Heightened sensitivity to normally non-painful stimuli (e.g. touch or temperature)
  • Declining benefit from previously effective opioid doses
  • Improvement in pain after reducing or ceasing opioid use
  • Emotional and cognitive effects from chronic opioid use
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How can we help

We use evidence-based therapies that can address OIH and aim to reduce opioid use

Our advanced therapies can reduce opioid induced heightened pain sensitivity, support safe opioid reduction, and help patients regain quality of life.

Ketamine therapy

Ketamine therapy interrupts abnormal pain signalling and calms central sensitisation, reducing hyperalgesia and improving function. It can also assist in reducing opioid use, provide relief during opioid tapering and ease withdrawal-related pain flare-ups. In clinical practice, ketamine may be considered as part of a specialist treatment plan to support people with opioid-induced hyperalgesia and to assist with opioid reduction.

Any opioid reduction plan should be medically supervised. Ketamine therapy, where appropriate, may be used as an adjunct within a structured care pathway.

Mental Health Conditions

DepressionPost traumatic stress disorder (PTSD)Suicidality

Pain Conditions

Neuropathic (nerve) painFibromyalgia/chronic widespread pain disordersChronic PainComplex regional pain syndrome (CRPS) MigraineCentral sensitisationOpioid use reductionOpioid Induced Hyperalgesia (OIH)
Ketamine therapy
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Our unique approach

Managing opioid induced hyperalgesia requires more than reducing medication — it requires restoring balance to the nervous system.

At Anodyne, we assess each patient’s pain profile carefully and use evidence-based treatments to help recalibrate the body’s pain pathways and restore effective pain control.

What to expect

Develop individualised treatment plans tailored to your history, current opioid use, and health goals

1.
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We work with your GP and specialist team to plan a safe opioid taper, minimise withdrawal while improving pain control

2.
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Manage both physical and psychological aspects of opioid use

3.
woman stretching back appearing in pain

Coordinate access to allied health and psychological support for long-term recovery

4.
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Why choose Anodyne?

We recognise how discouraging it can be when pain worsens despite higher medication doses.

We offer safe, evidence-based care for people experiencing OIH and treatment-resistant pain. Our ketamine therapies for opioid reduction aim to not only mitigate pain sensitivity but also help patients move forward with less reliance on opioids.


What defines our approach:

  1. Advanced, Evidence-Based Treatments
  2. Clinical Expertise in Psychiatry and Pain Medicine
  3. Collaborative, Multidisciplinary Approach


About Anodyne
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Want to know more?

Take the next step

If you suspect opioids may be making your pain worse, advanced alternatives are available. Book an appointment or make an enquiry to discuss whether ketamine therapy or a tailored reduction plan may be right for you.


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Frequently Asked Questions

Need to know more? Browse our frequently asked questions below.

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