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What Is Omalizumab?

Omalizumab is a prescription monoclonal antibody marketed under the brand name Xolair. It targets immunoglobulin E, also called IgE, which participates in allergic reactions. Omalizumab is approved for selected patients with allergic asthma, chronic rhinosinusitis with nasal polyps, IgE-mediated food allergies, and chronic spontaneous urticaria. It is administered by subcutaneous injection at intervals determined by the condition and individual characteristics. Omalizumab helps manage allergic disease but is not intended for immediate treatment of anaphylaxis or sudden asthma symptoms.

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What Is Omalizumab?

Omalizumab is a prescription monoclonal antibody marketed under the brand name Xolair. It targets immunoglobulin E, also called IgE, which participates in allergic reactions. Omalizumab is approved for selected patients with allergic asthma, chronic rhinosinusitis with nasal polyps, IgE-mediated food allergies, and chronic spontaneous urticaria. It is administered by subcutaneous injection at intervals determined by the condition and individual characteristics. Omalizumab helps manage allergic disease but is not intended for immediate treatment of anaphylaxis or sudden asthma symptoms.

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How Does Omalizumab Work?

Omalizumab binds to circulating IgE and reduces its ability to interact with receptors on mast cells, basophils, and other immune cells. This decreases allergic signaling and the release of substances involved in inflammation. Reduced IgE activity can help control symptoms in certain allergic and inflammatory disorders. Its effects depend on the condition being treated. Omalizumab does not directly relax airway muscles or immediately reverse a severe allergic reaction, so prescribed rescue medications remain necessary.

What Conditions Does Omalizumab Treat?

Omalizumab is approved for moderate to severe persistent allergic asthma in patients aged six years and older whose symptoms remain inadequately controlled with inhaled corticosteroids and who meet allergy testing criteria. It is also approved for chronic rhinosinusitis with nasal polyps in adults, IgE-mediated food allergy in patients aged one year and older to reduce reactions from accidental exposure, and chronic spontaneous urticaria in patients aged 12 years and older who remain symptomatic despite H1 antihistamines. Each indication has separate eligibility and treatment requirements.

How Is Omalizumab Administered?

Omalizumab is administered by subcutaneous injection, generally every two or four weeks for allergic asthma, nasal polyps, and food allergy, depending on the prescribed regimen. Dosing for these conditions is determined by pretreatment IgE levels and body weight. Chronic spontaneous urticaria commonly uses 150 mg or 300 mg every four weeks, independent of IgE levels or body weight. Treatment is initiated in a healthcare setting because of the risk of anaphylaxis. Selected patients can later administer injections at home after appropriate assessment and training.

What Are the Side Effects and Warnings of Omalizumab?

Common side effects can include injection-site reactions, headache, joint pain, and fatigue, with frequencies differing by indication. Omalizumab carries a boxed warning for anaphylaxis, which can occur after the first injection or after prolonged treatment. Other concerns include cardiovascular and cerebrovascular events, certain parasitic infections, and rare immune-related reactions. Patients should continue prescribed allergy avoidance measures and rescue medications. Difficulty breathing, throat swelling, fainting, or a severe allergic reaction requires immediate emergency medical care.

Common Questions About Omalizumab

Is omalizumab the same as Xolair?

Yes. Xolair is the brand name for omalizumab, a monoclonal antibody that binds to IgE.

Can omalizumab treat food allergies?

Yes. Omalizumab is approved for patients aged one year and older with IgE-mediated food allergy to reduce allergic reactions caused by accidental exposure. Patients must continue avoiding their food allergens.

How often is omalizumab injected?

Injection schedules depend on the condition. Omalizumab is generally administered every two or four weeks, with doses determined by the indication and other clinical factors.

Can omalizumab stop anaphylaxis?

No. Omalizumab is not an emergency treatment for anaphylaxis. Epinephrine remains the first-line emergency medication for suspected anaphylaxis.

References

DailyMed - XOLAIR (omalizumab) injection. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=7f6a2191-adfb-48b9-9bfa-0d9920479f0d. Date Accessed October 22, 2026.

FDA Approves First Medication to Help Reduce Allergic Reactions to Multiple Foods After Accidental Exposure. U.S. Food and Drug Administration. https://www.fda.gov/news-events/press-announcements/fda-approves-first-medication-help-reduce-allergic-reactions-multiple-foods-after-accidental. Date Accessed October 22, 2026.

Omalizumab. LiverTox. https://www.ncbi.nlm.nih.gov/books/NBK548822/. Date Accessed October 22, 2026.

Omalizumab. PubChem. https://pubchem.ncbi.nlm.nih.gov/compound/Omalizumab. Date Accessed October 22, 2026.

Omalizumab Injection. MedlinePlus. https://medlineplus.gov/druginfo/meds/a603031.html. Date Accessed October 22, 2026.