Urticaria
Characteristics and Causes
- Time to onset: immediate, accelerated (hours), or delayed (days).
- Type I hypersensitivity reactions: antibiotics (cephalosporins, and sulfonamides), local anesthetics, radiocontrast media, blood products, and gamma globulin.
- Non-immune urticaria: radiocontrast media and long-acting ACE-inhibitors (due to changes in vascular response to bradykinin).
- Mast cell degranulation by non-IgE mechanisms: opiate analgesics, anesthetic muscle relaxants, and Vancomycin (Red Man Syndrome, which can be worsened by concommitant opiate use).
