Allergic reactions to contrast media: accumulated evidence.

The allergic, antibody-mediated hypothesis of contrast medium reactivity, a nearly abandoned theory, is reconsidered in light of recently available clinical and laboratory data which support it. Anti-contrast-medium antibodies have been observed in patients suffering severe reactions and the triiodinated contrast medium moeity has been shown to be an effective hapten in experimental animals. Acceptance of an allergic hypothesis for contrast medium reactivity does not exclude alternative mechanisms for certain reactions.