Opioids after surgery can, paradoxically, prolong pain

Giving opioids to animals to quell pain after surgery prolongs pain for more than three weeks and primes specialized immune cells in the spinal cord to be more reactive to pain, according to a new study by CU Boulder.

The authors say the paradoxical findings, if replicated in humans, could have far-reaching implications for patient pain management and add a new wrinkle to the conversation about the national opioid epidemic.

“This indicates that there is another dark side of opiates that many people don’t suspect,” said senior author Linda Watkins, a professor in the Department of Psychology and Neuroscience. “It shows that trauma, including surgery, in combination with opiates can lead to chronic pain.”

Comment: There’s increasing evidence that opioids relieve pain in the short term and worsen it over the long run. This new experimental evidence suggests that the adverse effects of treatment with opioids may begin after just a few days of treatment. And these effects can last for weeks or months. Opioids worsening pain is called opioid-induced hyperalgesia. This isn’t tolerance to opioids: that as you continue to take them, you need a higher dose to get the same effect. It’s that through a different mechanism from pain relief, opioids actively make pain worse. Exactly how and when this occurs is still unclear. No one knows how to distinguish it from an underlying chronic pain condition. The only way to tell right now is that as you slowly diminish the opioid dose, people begin to feel better. We may find it’s much more pervasive than anyone had suspected. But nobody knows for sure.