Omalizumab and the World Health Organization. It is also used to treat people 12 years and above with chronic spontaneous urticaria (also called chronic idiopathic urticaria), which cannot be treated with elevated doses of H1-antihistamines. The main adverse effect is anaphylaxis (a life-threatening systemic allergic reaction), with a rate of occurrence of 1 to 2 patients per 1,000. Like other protein and antibody drugs, omalizumab also causes anaphylaxis, although at a relatively low frequency among antibody drugs. The allergic reaction is probably not due to the binding characteristics of the antibody drug, but to the protein nature of the antibody. The
Allergic transfusion reaction Allergic transfusion reaction An allergic transfusion reaction is a blood transfusion that results in allergic reaction. It is among the most common transfusion reactions to occur. Reported rates depend on the degree of active surveillance versus passing reporting to the blood bank. Overall, they are estimated to complicate up to 3% of all transfusions. The incidence of allergic transfusion reactions is associated with the amount of plasma in the product. More than 90% of these reactions occur during transfusion. Allergic reactions from blood transfusion may occur from the presence of allergy-causing antigens within the donor's blood, or transfusion of antibodies