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 composition, wherein the composition comprises an antihistamine, to form a vapor; and, b) allowing the vapor to cool, thereby forming a condensation aerosol comprising particles with 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 coating of an antihistamine drug composition and b) a device for dispensing said thin coating as a condensation aerosol.