Some articles on anaphylactoid:

Radiocontrast Agent - Adverse Effects - Anaphylactoid Reactions
... Anaphylactoid reactions occur rarely, but can occur in response to injected as well as oral and rectal contrast and even retrograde pyelography ... with a history of contrast reactions, however, are at increased risk of anaphylactoid reactions ... Anaphylactoid reactions range from urticaria and itching, to bronchospasm and facial and laryngeal edema ...