Pharmacy Clinical Pearl of the Day: Allergy Types

An overview of the four main types of allergies.

Clinical Pearl of the Day: Allergy Types

There are 4 main types of allergies.


  • Type 1: IgE immune reaction, immediate hypersensitivity, 5-30 minutes reaction, causes mast cell activation and presents as allergic rhinitis, asthma, or anaphylaxis.
  • Type 2: IgG/IgM immune reaction, antibody-mediated cytotoxic hypersensitivity, takes minutes to hours for reaction, causes complement mediated phagocytosis and presents as drug allergy, Graves disease, and anemia.
  • Type 3: IgG/IgM immune reaction, immune complex-mediated hypersensitivity, take 3 to 8 hours for reaction, causes tissue damage induced by immune complexes, and presents as rheumatoid arthritis, serum sickness, and SLE.
  • Type 4: T cell reaction, cell-mediated hypersensitivity, takes 48 to 72 hours for reaction, causes T cell mediated inflammation or cytotoxicity and presents as contact dermatitis, graft rejection, and chronic asthma.