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Xolair (omalizumab)

Xolair (omalizumab) is an anti-IgE antibody. Xolair is approved to treat people ages 6 years and up with moderate to severe persistent asthma and a proven allergy to a year-round allergen.1 You should have a skin or blood allergy test to confirm your allergies. Xolair is intended to treat people whose asthma is not controlled with inhaled corticosteroids. It is also approved to treat people with chronic hives without a known cause. It is made by Genentech Inc. Xolair is taken by injection.

Do not take Xolair if you are having an asthma attack.1 Use a rescue inhaler (short-acting beta agonist) instead.

How does Xolair work?

Xolair works by blocking IgE.1 IgE is an antibody that is responsible for many allergy symptoms. Xolair prevents IgE from turning on inflammatory cells called mast cells and basophils. This reduces symptoms such as wheezing, coughing, swelling, itching, and runny nose.2,3 Xolair is a monoclonal antibody made using biotechnology.1

How is Xolair taken?

Xolair is taken by an under-the-skin injection.1 It is taken every two or four weeks. The dose and frequency depends on your IgE levels and body weight. Your IgE levels are checked with a blood test. The injection is given in your health care provider’s office.4

What are the risks of taking Xolair?

Xolair can cause a life-threatening allergic reaction, called anaphylaxis.2 The reaction can happen the first time you take Xolair, but it can also happen after you have taken many doses. You will have to wait in your health care provider’s office after each injection in case of an immediate reaction. However, a reaction also can happen days later. If you have symptoms of an allergic reaction, go to the emergency department immediately. According to the product insert, signs of a serious reaction are:2

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

Studies of Xolair indicate that anaphylaxis occurs in 0.1% to 0.2% of people who take this medication.1
Some people who took Xolair had chest pain, heart attack, blood clots, temporary weakness on one side of the body, slurred speech, or altered vision.2 Whether Xolair caused these symptoms is not known.

What are the possible side effects of taking Xolair?

Common symptoms of taking Xolair are: pain in the arms and legs, dizziness, feeling tired, skin rash, bone fractures, injection site reactions, sore throat, and earache.2 You may have a fever, muscle aches, or rash within five days of taking Xolair.

People who take Xolair may have an increased risk of infections, including a higher risk of a worm (parasitic) infection and certain types of cancer.2 Tell your healthcare provider if you have had cancer or parasitic infections before. This is not an exhaustive list of side effects that could occur with Xolair and others may occur. Please make sure to discuss with your doctor.

Are there people who should not take Xolair?

Do not take Xolair if you are having an asthma attack.1 Use a rescue inhaler instead.

Tell your health care provider about any other allergies you have, such as food or seasonal allergies.2 You should also mention if you have had any sudden breathing problems or anaphylaxis. Tell your health care provider about any prescription or over-the-counter medications and supplements that you take.

Xolair has not been well studied in pregnant or breastfeeding women.2 Little is known about whether this medication passes into breast milk. Talk to your doctor about if you become pregnant or wish to breastfeed while taking Xolair. A pregnancy registry has been set up. The purpose of the registry is to track the outcomes for women who take Xolair while pregnant. Results from the registry were published in 2015.5 Of 188 women who took Xolair during their first trimester, there was no apparent increase in major birth defects.

If you are allergic to any ingredient in Xolair, you should not take this medication.2

What evidence do we have that Xolair works?

Xolair was studied in three high-quality studies.1 The studies compared Xolair with fake treatment (placebo). These studies included more than 1400 people with moderate to severe asthma. Everyone in the trials was allergic to a year-round allergen.

In two of the studies, participants were taking inhaled corticosteroids and rescue medications, but they were still having asthma symptoms. The people who got Xolair had fewer asthma attacks, fewer asthma symptoms during the day or night, and better lung function.

In the third study, some participants took long-acting beta agonists and oral corticosteroids in addition to inhaled corticosteroids and rescue medications. In this study, the people who took Xolair had the same number of asthma attacks as the people who took placebo.

People with relatively good lung function at the start of the study did not benefit from Xolair. People who took long-term oral corticosteroids also did not benefit from Xolair.

Is there a generic alternative to Xolair?

No, there is no generic alternative to Xolair.

Written by: Sarah O'Brien | Last Reviewed: September 2019.
  1. Xolair® [prescribing information]. South San Francisco, CA: Genentech, Inc; 2014.
  2. National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma - Full Report 2007. Accessed 11/12/14 at:
  3. IgE's role in allergic asthma. Asthma and Allergy Foundation of America. Available at:
  4. Xolair® [patient information]. South San Francisco, CA: Genentech, Inc; 2014.
  5. Namazy J, Cabana MD, Scheuerle AE, et al. The Xolair Pregnancy Registry (EXPECT): The safety of omalizumab use during pregnancy. J Allergy Clin Immunol. 2015;135:407-412.