The purpose of the research is to study the allergenic and immunotoxic properties of pantohematogen obtained from the blood of female Gorno-Altai maral deer as a functional ingredient of specialized products. Allergenic and immunotoxic properties were assessed in 2020–2022 by intragastric administration of pantohematogen to 395 CBA mice weighing 15–18 g, who received the drug at a therapeutic dose of 50 mg/kg and a maximum single dose of 500 mg/kg. The sensitization of the animal body after a course of administration of pantohematogen was determined by deregulation of mast cells. It has been established that when using the maximum single dose, the degranulation reaction does not exceed 0.2. It is necessary to emphasize that no changes in the leukocyte lysis coefficient were recorded in mice receiving different doses of pantohematogen. The effect of pantohematogen on the mass and cellularity of the immunocompetent organs of animals is also shown. It was noted that even the use of a dose (500 mg/kg) 10 times higher than the therapeutic dose does not affect the cellularity of immunocompetent organs. In general, the materials of experimental studies indicate the absence of allergenic and immunotoxic properties of the tested pantohematogen as a functional ingredient in the development of specialized products with specified therapeutic and prophylactic properties.