Xolair (Omalizumab): Treatment for Allergic Asthma

Safety, side effects, and more

Xolair (omalizumab) is an injectable medication used to treat moderate to severe allergic asthma. It's used in people 6 years and older who still have uncontrolled asthma despite treatment with standard asthma therapies, including inhaled steroids. Injections are given in the healthcare provider’s office every two to four weeks, with doses and frequency depending on a person’s weight and allergic antibody (IgE) level.

Woman with hand on her chest struggling to breathe

BSIP / UIG / Getty Images 

What Exactly Is Xolair?

Xolair is a monoclonal anti-IgE antibody that binds to IgE antibodies in the bloodstream.

Normally, excess IgE antibodies attach to mast cells and bind to allergens, causing the release of histamine and other chemicals into the bloodstream. These chemicals cause worsening asthma and other allergy symptoms.

The medication prevents IgE from attaching to mast cells and binding to allergens, It has been shown to decrease the frequency of asthma attacks, improve the overall quality of life for people with asthma, and reduce the need for corticosteroids.

Generally, it can take a few months of injections for Xolair to begin to work.

Xolair is not a cure for asthma—symptoms would be expected to worsen a few months after Xolair therapy is stopped.

The medication can be expensive.


Xolair currently has a “black box” warning, which is a precautionary statement given to the medication by the U.S. Food and Drug Administration (FDA). This warning has come about as a result of reports of people experiencing anaphylaxis (allergic reaction) after receiving Xolair.

While there are no reports of fatal anaphylaxis as a result of Xolair, some cases have been serious and potentially life-threatening. For this reason, the FDA requires that people receiving Xolair be monitored in their healthcare provider’s office for a period of time after their injections. The specific amount of time is determined by the healthcare provider.

People who receive Xolair should watch out for the following symptoms of anaphylaxis, which could occur up to 24 hours (or longer) after the injection:

  • Wheezing, shortness of breath, coughing, chest tightness, or trouble breathing
  • Low blood pressure, dizziness, fainting, rapid or weak heartbeat
  • Flushing, itching, hives, or swelling
  • Nausea, vomiting, diarrhea, or abdominal pains
  • Swelling of the throat, tongue, lips, or eyes
  • Throat tightness, hoarse voice, trouble swallowing
  • Sudden severe sneezing, severe runny nose, or nasal congestion
  • Anxiety or feeling of panic

If you experience any of these symptoms, it is important to notify your healthcare provider immediately. Many healthcare providers prescribe injectable epinephrine for patients to use in the case of anaphylaxis 24 hours after their Xolair injection.

The drug is produced in mice and therefore contains approximately five percent mouse protein It does not appear that an allergy to mouse protein causes problems for people receiving Xolair.

Increased Cancer Risk

During clinical development, rates of cancer were slightly higher in people receiving Xolair compared to people receiving placebo injections. The types of cancers seen in people receiving Xolair include breast cancer, skin cancer, prostate cancer, or salivary gland cancer. It is not yet known what the potential long-term effects of Xolair use may have on people who are prone to getting cancer.

The serious side effects of anaphylaxis and cancer occurred in a very small number of patients. It is still not known why these side effects occur, although studies are ongoing to determine the reason.

Uncontrolled asthma can lead to severe complications, including death. And medications used to treat asthma attacks, such as oral and injected corticosteroids, can cause serious side effects with long-term use. Make sure you discuss all of your questions and concerns about the risks and benefits of taking Xolair with your provider.

Xolair for Other Health Conditions

Xolair is also used to treat nasal polyps in people 18 years of age and older when medicines such as nasal corticosteroids have not worked well.

Studies have examined the benefit of Xolair for the treatment of chronic idiopathic urticaria (hives)—CIU. In March 2014, the FDA approved the use of Xolair for CIU.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Novartis Pharmaceuticals Corporation. Xolair.

  2. Galli SJ, Tsai M. IgE and mast cells in allergic disease. Nat Med. 2012;18(5):693-704. doi. 10.1038/nm.2755

  3. John Hopkins Medicine. Patient Information Letter. Xolair (Omalizumlab).

  4. Food and Drug Administration. Xolair (omalizumab) label.

  5. Lynn SJ. An asthma drug and anaphylaxis: a stronger warning. AJN, American Journal of Nursing. 2007;107(6):35. doi. 10.1097/01.NAJ.0000271843.84918.57

  6. American Academy of Allergy Asthma & Immunology. Omalizumab administration recommendations.

  7. American College of Allergy, Asthma, & Immunology. Anaphylaxis.

  8. Liu P, Pan Z, Gu C, et al. An omalizumab biobetter antibody with improved stability and efficacy for the treatment of allergic diseases. Front Immunol. 2020;0. doi. 10.3389/fimmu.2020.596908

By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.