Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a ziprasidone stimulus. Ziprasidone is a piperazine compound having 1,2-benzothiazol-3-yl- and 2-(6-chloro-1,3-dihydro-2-oxindol-5-yl)ethyl substituents attached to the nitrogen atoms.