The term "allergenic" refers to substances that trigger allergic reactions in individuals. There are several synonyms for this word such as allergic, antigenic, sensitizing, and irritant. Allergic substances are those that cause an immune response in the body. Antigenic substances are those that stimulate an immune response by producing antibodies. Sensitizing substances are those that make the skin or other body parts more sensitive to allergens. Irritant substances are those that cause irritation in the body, which may be an underlying cause of allergic reactions. These synonyms explain the characteristics of the allergenic substance and how they can lead to different types of allergic reactions.