Before beginning your treatment with Xolair, read the Product Insert that the manufacturer issues. If you have any questions, discuss these with the prescribing doctor or your healthcare provider. Talk to your healthcare provider if you experience any side effects described here or other unexpected ones.

The most common side effects of Xolair are:

• When treating asthma for people over the age of eleven – joint pain, especially in the arms and legs; dizziness; feeling tired; itching or skin rash; bone fractures; pain or discomfort in the ears
• When treating asthma in children twelve years of age and under – swelling inside the nose, throat, or sinuses; headache; fever; throat infection; ear infection; abdominal pain; stomach infection; nose bleeds
• When treating nasal polyps – headache; reactions at the injection site; joint pain; upper abdominal pain; dizziness
• When treating chronic spontaneous urticaria – nausea; headaches; swelling inside the nose, throat or sinuses; cough; joint pain; upper respiratory tract infection.

These are not the only possible side effects. Call your doctor for medical advice if these or any other side effects persist or worsen.

There is a rare but serious possible side effect called anaphylaxis, which can happen either immediately or days later after receiving a dose of Xolair. Anaphylaxis is a life-threatening condition and can lead to death. Go to the nearest emergency room right away if you have any of these symptoms of anaphylactic shock:

• wheezing; shortness of breath; cough; chest tightness; trouble breathing
• low blood pressure; dizziness; fainting; rapid or weak heartbeat; anxiety; a feeling of “impending doom”
• flushing; itching; hives; feeling warm
• swelling of the throat or tongue; throat tightness; hoarse voice; trouble swallowing

Xolair is prescribed for the following conditions:

• moderate to severe persistent asthma in people six and older. It will be prescribed only if the asthma symptoms are not well controlled with inhaled corticosteroids
• nasal polyps in people eighteen years of age and older. It can be prescribed  when nasal corticosteroids have not worked well enough, or the patient is allergic to steroids
• chronic hives without a known cause, labeled chronic spontaneous urticaria (CSU), in people twelve years and older. It is prescribed when the hives cannot be controlled with H1 antihistamine treatment.

It is yet to be determined whether Xolair is effective for people younger than the ages specified.

Xolair works by inhibiting the binding of the IgE molecule in specific cells of the immune system that contain histamine and heparin (mast cells and basophils.) By inhibiting the binding of IgE molecules, Xolair will lower the histamine levels, and so ward off or reduce any asthma attack or hives, and shrink nasal polyps.

Histamine has many inflammatory effects on the body, one of which is to contract the smooth muscle tissue in the lungs. A flood of histamine can cause wheezing and make breathing difficult, along with flu-like symptoms (runny nose and watery eyes). It can also cause tissue swelling, itchy skin, and hives. Histamine is also one of the main chemicals involved in anaphylaxis, a severe and sometimes fatal allergic response to a previously encountered allergen.