Antibodies are proteins people make, generally to fight infections. IgE is a very special type of antibody made by people with allergies. When people with allergies are exposed to their allergic triggers, the substances they're allergic to combine with IgE to trigger an allergic reaction. Part of the allergic reaction involves creating airway inflammation, which can lead to asthma symptoms or attacks).
Xolair® (or omalizumab) is a medication designed to block human IgE antibodies. It is currently licensed in Canada for individuals 12 years of age and older. It is given by injection, every 2 to 4 weeks (rather like allergy shots). However, by blocking all human IgE antibodies, it can help prevent most types of allergic reactions from leading to worsening asthma. Studies have shown that treatment with Xolair® leads to modest improvements in asthma severity, particularly in patients on inhaled steroids. It can only be used in patients with mild-moderately increased blood levels of IgE, because patients with too high blood IgE levels need a dose of Xolair® that is too high to administer. Thus, it is generally not available for patients with very severe allergies, who tend to have very high blood IgE levels (many times, these patients also have severe eczema). Side effects of this medication are infrequent. A few patients develop swelling or other local reactions where the medication is injected. Extremely rarely, people may have allergic reactions to this medication. Xolair® is currently very expensive, and is generally used only in patients with quite severe asthma, who have mild-moderately increased blood IgE levels.
Allergy shots (or immunotherapy) are a series of injections which contain very tiny amounts of a substance a person is allergic to. Giving these injections, in slightly increasing amounts over a long period of time may gradually make the person less likely to have an allergic reaction when exposed to a larger amount of this substance. Allergy shots can be helpful in people with hay fever (or allergic rhinitis) who are allergic to a particular pollen which is present a certain time of the year, such as ragweed. Unfortunately, most people with asthma triggered by allergies are allergic to many different things, and making these people less sensitive to one or two particular allergens usually has little impact on their overall asthma control. In addition, people with asthma are more likely to have severe reactions to allergy shots than people who have allergies alone. Because of these reasons, most doctors do not recommend allergy shots for children with asthma. If allergy shots are used, they should be given very carefully and are usually only used in particular situations, such as the child who really seems to be only allergic to one or two things, and who has no other triggers.