Opioid induced hyperalgesia (OIH) and Hyperkatefia: The clinical and experimental phenomenon whereby patients taking opioids paradoxically become more sensitive to nociceptive (pain provoking) stimuli directly due to opioid effects. OIH is considered to be due to allostatic opponent effect on the sensory (nociceptive) component of pain generating processes. OIH is clinically rare but easier to prove experimentally. The clinical effect of allostatic opponent effect on the emotional and cognitive parts of the pain process has been called hyperkatefia (the so-called emotional pain). OICP can be considered a combination of OIH and hyperkatefia, but OIH is infrequent.