the present invention relates to the delivery of antihistamines through an inhalation route . specifically , it relates to aerosols containing antihistamines that are used in inhalation therapy . in a method aspect of the present invention , an antihistamine is delivered to a patient through an inhalation route . the method comprises : a ) heating a thin layer of an antihistamine , on a solid support , to form a vapor ; and , b ) passing air through the heated vapor to produce aerosol particles having less than 5 % antihistamine drug degradation products . in a kit aspect of the present invention , a kit for delivering an antihistamine through an inhalation route is provided which comprises : a ) a thin layer of an antihistamine drug and b ) a device for dispensing said thin layer as a condensation aerosol .