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Medicine

Opioid-induced hyperalgesia versus tolerance in chronic pain

Quick fact

A key clinical puzzle: patients on chronic opioids may experience worsening pain even as the dose increases, a condition known as opioid-induced hyperalgesia (OIH). OIH is distinct from tolerance—increasing the dose further can worsen the pain, while dose reduction may actually improve it.

Why this is interesting

You might think that taking a stronger dose of opioid painkiller would always give better pain relief. But sometimes, the opposite happens: the drug itself can make the pain worse.