👉 In medical terminology, "hypersensitivity" refers to a physiological reaction that occurs when an organism is exposed to a substance or antigen that it has not encountered before. This response can be either positive (i.e., beneficial) or negative (i.e., harmful), depending on the severity of the hypersensitivity. Typically, hypersensitivities are characterized by a sudden and rapid increase in symptoms following exposure to a particular substance or antigen. These symptoms may include increased heart rate, sweating, trembling