Physiologic | Hypersensitivity | |
Type of reaction (and other terminology used) | Physiologic (also called toxic, chemotoxic). | Hypersensitivity (also called allergy-like, allergic-like). |
Timing relative to administration | Within minutes to 1 hour by definition. Often within seconds. | Within minutes to 1 hour by definition. |
Signs and symptoms |
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Predictability |
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Possible pathophysiology | Possibly related to direct chemotoxicity, osmotoxicity, or binding of agent to endogenous molecules. | Mechanism of mild reactions is unclear; direct mast cell activation has been proposed. Some reactions in reexposed patients may be IgE mediated. |
Severity | Most are mild and self-limited. | Most are mild and self-limited, but severe reactions can be fatal. |
Risk factors | High dose and osmolarity, angiography. | Previous immediate hypersensitivity reaction. |
Allergy testing indicated? | No. | Yes, especially for moderate-to-severe reactions. Premedication is usually effective for preventing recurrences of mild reactions. |
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