Compositions and methods are provided for reducing adverse reactions as a result of parenteral administration of certain phenothiazine derivatives such as promethazine hydrochloride. The active compound may be admixed with an effective amount of one or more cyclodextrin derivatives, and if desired, one or more non-ionic surfactants such as the partial esters of sorbitol and the polyoxyethylene oxides of long chain fatty acids such as the polysorbates.