Delayed onset and protracted progression of anaphylaxis after omalizumab administration in patients with asthma.

Background: Risk of anaphylaxis is included in the prescribing information for omalizumab, but the nature of these reactions merits further elaboration.

Objective: To describe cases of anaphylaxis associated with omalizumab administration in patients with asthma.

Methods: We reviewed spontaneous postmarketing adverse event reports submitted to the US Food and Drug Administration's Adverse Event Reporting System database and to the manufacturers of omalizumab and cases published in the literature through December 2006.