BACKGROUND: Pain is one of the most common clinical symptoms . This review aims 
to describe research on herbs and their active ingredients in treating pain and 
provide a valuable reference for the development and utilization of analgesic 
traditional Chinese medicine (TCM).
MATERIAL AND METHODS: The literature search was performed from 1995 to October 
2016, covering the relevant studies 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.
RESULTS: There are two pathways constituting the analgesic mechanisms of TCM: 
through the central nervous system and 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 
tissues, blocking the central calcium channel, reducing excitatory amino acids 
in brain tissues, inhibiting their receptors and raising the content of the 
central 5-hydroxytryptamine (5-HT). The latter one usually involves the decrease 
in the secretion of peripheral algogenic substances, the induction of 
pain-sensitive substances, the accumulation of a local algogenic substance, the 
increase in the release of peripheral endogenous analgesia materials and the 
regulation of c-Fos gene (immediate early gene).