Pain and addiction share some common physiologic pathways
in the brain, especially those involving opioids, and each may
affect the other. That is, the presence of pain may influence the
development and course of opioid addiction, and vice versa
(Compton and Gebhart 2003).
These interactions may complicate therapy for opioid addiction.
For example, opioid-addicted persons appear to have lower tolerance
for and greater sensitivity to pain, and this may continue during
addiction treatment. Sleep disorders and psychiatric illness often
associated with addiction may increase the experience of pain
and decrease the effectiveness of pain-relief interventions. Furthermore, opioid medications
may lose their analgesic potency in many of these patients, so the management of their pain
can be challenging (Compton and Gebhart 2003).

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