Define hypersensitivity reaction.
an exaggerated and/or pathological immune response to foreign or self antigens
an abnormal immunological response to an otherwise harmless environmental stimulus (e.g., food, pollen, animal dander)
Define drug hypersensitivity reaction.
group of adverse drug effects that resemble an allergy (may be allergic or nonallergic)
Describe the stages of hypersensitivity reactions.
Sensitization (immunology): initial asymptomatic contact with an antigen
Effect: harmful immune response following subsequent antigen contact
Describe the classification.
Traditionally categorized into four types based on immunological mechanisms
Reactions may be heterogeneous (i.e., syndromes do not fit into a single category).