Abstract: The current invention provides formulations for transdermal delivery of promethazine which achieve delivery of the drug with consistent plasma levels. The topical formulations of the invention are superior to both rectal suppositories and oral dosage forms in that variable blood levels, first-pass metabolism, unpredictable peaks in blood levels, and variable bioavailability are minimized. Formulations of the invention provide antiemetic and antipruritic relief to patients in need of treatment while minimizing side effects and adverse reactions known to occur with other routes of administration and other formulations.