a method treats or prevents neuropathic pain with a synergistically - enhanced analgesic effect at a dose at which a calcium channel α2δ ligand does not produce any side effects as well as which agent does not produce any new side effects on the central nervous system . the therapeutic agent or a prophylactic agent used in the method includes as effective ingredients a cyclohexane derivative or a pharmaceutically acceptable salt thereof or a prodrug thereof , and a calcium channel α2δ ligand .