OBJECTIVE: To systematically review the involvement of K BACKGROUND: K METHODS: PubMed and Embase databases were searched until 29 January 2024, using the following search string: [(pain) OR (nociception) OR (antinociception) AND (K RESULTS: The search resulted in 569 records. In total, 126 duplicates were detected. Subsequently, 438 records were screened by title and abstract, resulting in the exclusion of 396. Based on inclusion criteria, 42 studies were included. The main findings of the present systematic review were that K CONCLUSION: Local, systemic, spinal, and supraspinal activation of K