Paroxetine, or a P2X4 receptor antagonist such as a diazepine dione derivative that is represented by general formula (IX) is used as a preventive or therapeutic agent for pain associated with herpes zoster in acute phase. (In the formula, R1 represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and the like, R2 and R3 represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and the like, R4 and R5 represent a hydrogen atom and the like, and W represents a five- or six-membered ring heterocycle containing 1 to 4 nitrogen atoms as an element of ring that may have a substituent.)
