Opioid Painkillers Can Increase Pain

Article Summary: Opioids can paradoxically induce severe pain

Berthelot, Nizard and Maugars - Joint Bone Spine, 85 (2018) 655–657

As previously discussed on the Wrinkle Well blog “Opioids: A Surgeon’s Perspective” the issue of opioid addiction has been prominent in the media over recent years. Opioid medications are strong, potentially addictive prescription drugs used for severe pain and following surgery. But how effective are they really? Might they sometimes be doing the opposite, and increasing pain?

Research published in 2018 has found that in some circumstances - especially when used for a prolonged period - opioid medications can increase the intensity, frequency and area of pain. They may even, in some people, cause normal sensations such as a light touch on the skin to feel painful.

This process of increasing pain – called opioid-induced hyperalgesia – has been recognised for decades but was incorrectly assumed to be the result of the patient developing a tolerance to the medication. They feel more pain over time, so their dose is increased and temporarily they feel their pain levels reduce. But then, the pain increases again, and the cycle continues.

The more recent research provides a new insight into the effect of opioid medication at a cellular and chemical level in the nerves, spinal cord and brain where pain is processed. Our body has systems that “turn down”, filter or control pain messages, and these systems become less effective with opioid use. Meanwhile, the systems that “turn up”, alter and distort pain messages become more effective. In some people these changes occur even after a single dose of opioids, but they become very common after prolonged use.

For the patient, this typically means a heightened sensitivity to pain (called hyperalgesia), a spread of pain into previously pain-free areas of the body, and pain during previously non-painful sensations (called allodynia). This increased pain sensitivity may take months or even years to resolve after opioid medications are ceased, and in some cases it never completely resolves.

Some people seem more susceptible to these opioid-induced changes – likely related to genetic factors and psychological stress. However, they can potentially effect anyone who uses opioid-based pain medication. These findings have resulted in most major medical practicing bodies recommending that opioid medications are not effective for treating long-term or chronic pain, and that any prescription of opioids needs to consider the high risks of addiction, overdose and opioid-induced hyperalgesia.