Introduction: Pain is one of the most common symptoms in clinical. This review is to describe researches on herbs and their active ingredients in treating pain and provide valuable reference for the development and utilization of analgesic traditional Chinese medicine (TCM).
Areas covered: The literature search was performed from 1995 to October 2016, covering the relevant literatures that concern the treatment of pain with TCM. Active ingredients extracted from TCM with analgesic activity are summarized and classified into six categories, including polysaccharides, saponins, alkaloids, flavonoids, terpenoids and other constituents.
Expert opinions: There are two pathways constituting the analgesic mechanisms of TCM: through the central nervous system and through the peripheral nervous system. The former pathway includes increasing the content of endogenous analgesic substances like opiate peptide, cutting down the second messenger of neurotransmitter like nitric oxide (NO), reducing the content of prostaglandin E2 (PGE2) in brain tissue, blocking the central calcium channel, reducing excitatory amino acids in brain tissue, inhibiting their receptors and raising the content of the central 5-hydroxytryptamine (5-HT). The latter one usually contains the decrease in secretion of peripheral algogenic substances, the induction of pain-sensitive substances and the accumulation of local algogenic substance, the increase in release of peripheral endogenous analgesia materials and the regulation of c-Fos gene (immediate early gene).