Adverse Events of the Long-Term Use of Opioids for Chronic Non-cancer Pain: A Narrative Review

BACKGROUND: The long-term use of opioids for chronic non-cancer pain (CNCP) has drawn more attention and debate. Although opioids are frequently used to treat chronic pain, their effectiveness and safety over extended periods are still unknown. OBJECTIVES: The purpose of this review is to provide an overview of what is currently known about the adverse events of long-term use of opioids in CNCP. It also delivers patient-centered strategies designed to mitigate these risks. METHODS: We conducted a literature search in PubMed, MEDLINE, EMBASE, and Web of Science databases. Search terms included CNCP, pain pathophysiology, opioid pharmacodynamics, opioid prescribing trends, guidelines for opioid use, and opioid side effects. Results: Our review highlights that while opioids may provide short-term relief from CNCP, their effectiveness diminishes over time due to the development of opioid tolerance. This tolerance often leads to increased dosages, which can subsequently result in opioid dependence. Additionally, long-term opioid therapy is associated with a spectrum of adverse effects, including constipation, drowsiness, respiratory depression, and potential for drug interactions. Furthermore, our review indicates that alternative pain management strategies play a crucial role in controlling CNCP. They offer significant benefits with fewer adverse events. These strategies include non-opioid medications, physical therapy, cognitive-behavioral therapy (CBT), various interventional procedures, injection therapy, and acupuncture. CONCLUSION: Using opioids to manage CNCP presents several challenges. Given these challenges, alternative treatments are being considered as viable options. Moreover, it is crucial to customize treatment plans to align with the patients' specific health requirements, existing conditions, and potential risks to ensure the best possible outcomes.