• Roi Treister, Elon Eisenberg, Eli Lawental, and Dorit Pud.
• Faculty of Social Welfare and Health Sciences, University of Haifa, Israel.
• J Opioid Manag. 2012 Nov 1;8(6):343-9.

ObjectiveHyperalgesia has been observed in active opioid addicts (OAs). The aim of this study was to explore whether opioid-induced hyperalgesia (OIH) is a reversible phenomenon.DesignObservational study.ParticipantsThe study included the following three groups of male subjects: 1) active addicts on heroin or methadone (OAs, n = 50); 2) former opioid addicts with at least 5 months of abstinence from drug use (FOAs, n = 43); and 3) drug naïve controls (C, n = 50).InterventionsAll subjects were exposed to the cold pressor test (1°C).Main Outcome MeasuresCold pain threshold (latency to pain onset, seconds) and cold pain tolerance (latency to pain intolerability, seconds).ResultsMean ± standard deviation (SD) pain thresholds were 10.8 ± 7.7, 6.9 ± 3.9, and 6.8 ± 3.5 seconds for the OAs, FOAs, and C groups, respectively (analysis of variance [ANOVA], p = 0.002, 95% CI = 7.5-9.2). Mean ± SD pain tolerance levels were 30 ± 36.2, 64 ± 58.1, and 56.4 ± 51.4 seconds for the OAs, FOAs, and C groups, respectively (ANOVA, p < 0.001, 95% CI = 43-60.4). Post hoc analyses revealed significant changes between the OAs and the other two groups for both variables.ConclusionsIt is suggested that altered pain perception in OAs is a reversible phenomenon that may require a long period of abstinence to reset, rather than being an individual long-term stable trait.

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