A method of inhibiting or reducing occurrence or intensity of pruritus including administering to a patient an effective amount of one or more of the morphinan derivative having a nitrogen-containing cyclic group of the Formula (Ia): ##STR00001## wherein R.sup.1 is cyclopropylmethyl; R.sup.2 and R.sup.3 are independently hydrogen, hydroxy, C.sub.1-C.sub.5 alkoxy, C.sub.3-C.sub.7 alkenyloxy, C.sub.7-C.sub.13 aralkyloxy or C.sub.1-C.sub.5 alkanoyloxy; and the Formula (Ia) includes (+), (-) and (.+-.) isomers or the pharmaceutically acceptable acid addition salt thereof.