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 histamine stimulus. Histamine, the biogenic amine 2-(1H-imidazol-4-yl)ethanamine, is involved in local immune responses as well as regulating physiological function in the gut and acting as a neurotransmitter.