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Is Xolair an immunosuppressant?

Medically reviewed by Carmen Pope, BPharm. Last updated on Nov 30, 2023.

Official answer

  • Xolair does act on the body’s immune system to prevent an allergic response, but because it only acts on the allergic arm of the immune system it does not appear to compromise the immune system as other immunosuppressants do.
  • Xolair is not like traditional immunosuppressants, such as prednisone or cyclosporine because it does not increase the risk of infection nor the risk of COVID-19.
  • Xolair binds with IgE, forming a stable, nonreactive complex that prevents IgE from acting on IgE receptors and causing histamine and heparin release which are responsible for allergic-type symptoms.

Xolair (omalizumab) is an antibody that may be used to treat allergic asthma that is:

  • Moderate-to-severe
  • Persistent
  • Not adequately controlled by inhaled corticosteroids
  • In adults and children aged 6 and over who have had a positive skin test to an allergen or who react to an allergen that is present in their environment year-round.

Xolair is also approved to treat:

  • Urticaria (hives) in adults and children aged 12 and older who have already tried antihistamines without success
  • Nasal polyps in adults aged 18 years and older.

Xolair is administered by injection under the skin (subcutaneously) once every two to four weeks. The dosage of Xolair is based on body weight.

How does Xolair work?

Xolair works by inhibiting the binding of IgE to IgE receptors on mast cells and basophils. Mast cells and basophils are specific cells of the immune system that contain histamine and heparin.

As soon as IgE binds to an IgE receptor it causes the release of histamine and heparin from the cell. Histamine is a chemical that has many inflammatory effects in the body. It contracts the smooth muscle tissue in the lungs, uterus, and stomach; dilates blood vessels causing an increase in permeability and a lowering of blood pressure; stimulates the secretion of gastric acid in the stomach; and speeds up the heart rate.

Histamine also causes symptoms such as a runny nose, watery eyes, tissue swelling, itchy skin, and hives. Because histamine contracts the breathing tubes it can cause wheezing or make it harder to breathe.

Histamine is also one of the main chemicals involved in anaphylaxis, a severe and often fatal allergic response to a previously encountered allergen.

Heparin is an anticoagulant that slows the formation of blood clots.

By inhibiting the binding of IgE to the IgE receptor, Xolair prevents the release of histamine and heparin and also reduces the number of IgE receptors on basophils.

Xolair forms stable Xolair/IgE complexes which are more slowly excreted from the body than free IgE. This means that total serum IgE levels (bound and unbound) will show an increase in laboratory testing; however, free IgE levels are decreased within an hour of injection, and decreases of greater than 96% have been reported.

IgE levels are increased in people with allergic asthma when they inhale allergens such as pet dander or dust mites which is why Xolair is effective at treating allergic asthma.

Xolair will not treat an acute asthma attack or status asthmaticus.

93% of people with moderate-to-severe chronic urticaria have increased total IgE levels. Xolair is not approved for the treatment of other allergic conditions.

Does Xolair lower immunity?

Because Xolair works on the allergic arm of the immune system, it does not appear to compromise the immune system like traditional immunosuppressants, such as prednisone and cyclosporine.

Xolair is not associated with an increased risk of infection nor increase the risk for COVID-19. However, Xolair is associated with other side effects, such as pain, including joint pain and leg pain, dizziness, fatigue, and a higher risk of cancer of the breast, skin, prostate, and parotid gland (incidence of 0.5% compared to 0.2% in those taking placebo).


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