Opioid-induced hyperalgesia (OIH)

Opioid-induced hyperalgesia is a paradoxical effect where long-term use of opioids makes patients more sensitive to pain rather than less.

It is thought to involve changes in the central nervous system, including activation of NMDA receptors, neuroinflammation and increased excitability of pain pathways. Clinically, patients may report worsening or spreading pain despite increasing opioid doses. Recognizing OIH is crucial, as treatment often involves tapering opioids and shifting toward alternative pain management strategies.