Newswise — Use of opioid pain medications may contribute to an increase in sensitivity to some types of pain, according to an Australian study published in The Journal of Pain.

Researchers sought to examine the effect of long-term opioid use in chronic noncancer pain patients and opioid-maintained patients to determine if the medications can cause hyperalgesia or allydonia. They examined three groups of subjects: chronic pain patients receiving treatment with methadone or morphine, methadone-maintained patients and healthy drug free individuals.

The research reported several significant findings. First, it confirmed that methadone-maintained patients demonstrated hyperalgesia and not allydonia when pain sensitivity was measured with the cold pressor test. This did not occur after electrical stimulation, however. A second finding showed that similar nociceptive profiles are found in chronic pain patients treated with methadone. Third, the study showed that pain sensitivity associated with methadone administration also is found in morphine-treated patients. According to the authors, the study demonstrated that hyperalgesia but not allydonia is associated with the long-term administration of opioids.

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The Journal of Pain