The search for new compounds with pharmacological activity is extremely important. The approach to the acquisition of a new range of medicinal agents by the existing set of biologically active compounds is extremely promising. This is achieved by using the methods of nanotechnology and mechanochemistry. In this paper, a comparative study of the pharmacological activity of loratadine submicrostructured substance and basic substance of loratadine was carried out on an experimental model of allergic contact dermatitis. The animals were sensitized by the method of Zalkan and Ievleva. The 5% ethanol-acetone solution of 2,4-dinitrochlorobenzene was used as an allergen. The development of contact allergic dermatitis was determined by the general condition and behavior of animals, as well as monitoring of the changes in the state of the skin at the site of application. The 5-day simulation of allergic contact dermatitis has resulted in an increase of cutaneous manifestations of allergic reactions. Besides, there has been noted an increase in the skinfold thickness at the site of allergen application. The results of the research of the basic and submicrostructured substance of loratadine have demonstrated the effectiveness in preventing cutaneous manifestations of allergic reactions. In groups of animals where submicrostructured and basic substance of loratadine were applied, in the setting of simulation of contact allergic dermatitis, there was observed a decrease in the thickness of the skin fold. The use of loratadine submicrostructured substance tended to be more efficient in comparison with the basic substance of loratadine.