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Omalizumab

Pronunciation: OH ma LIZ oo mab
Brand name: Xolair
Dosage form: Autoinjector (75 mg/0.5 mL, 150 mg/mL, 300 mg/2), Prefilled syringe (75 mg/0.5 mL, 150 mg/mL, 300 mg/2 mL), vial for reconstitution (150 mg)
Drug class: Selective immunosuppressants

Medically reviewed by Melisa Puckey, BPharm. Last updated on Jan 24, 2025.

What is omalizumab?

Omalizumab (Xolair) injection is used to reduce the risk of severe food allergy reactions (anaphylaxis) and help improve allergic asthma, nasal polyps, and chronic hives.  

Omalizumab is given as an injection under the skin every 2 to 4 weeks and can be self-injected using a pen (autoinjector) or a prefilled syringe. Omalizumab is an anti-IgE antibody that works by blocking a protein from your immune system called IgE, which helps to reduce allergy symptoms. Omalizumab is a preventative medicine that reduces symptoms caused by allergies; it does not treat acute asthma or emergency allergic reactions, including anaphylaxis.

Omalizumab FDA approval was granted on June 20, 2003, for Genetech and Novartis Pharmaceutical.

Omalizumab brand name is Xolair.

What is omalizumab used for?

Omalizumab is used to treat:

How does omalizumab work?

If you have allergies, your overactive immune system produces antibodies called Immunoglobulin E (IgE) which bind to receptors on cells in the immune system (mast cells). When you are exposed to the allergen (food, dust, grass) the allergen binds to IgE on the cells which sets off an allergic reaction triggering the release of chemicals like histamine, which causes the allergic reaction.

Omalizumab mechanism of action is by blocking the binding of IgE to receptors on cells, which in turn stops the release of the chemicals responsible for allergy symptoms. Omalizumab also reduces the number of IgE receptors on cells, resulting in further improvement of allergy symptoms.

Omalizumab side effects

Common omalizumab side effects

Common omalizumab side effects include: 

The common omalizumab side effects vary depending on the condition being treated and the age group of the patient. 

Serious omalizumab side effects

Some people using omalizumab have had a severe, life-threatening allergic reaction either right after the injection or hours later. Allergic reactions may occur even after using the medication regularly for a year or longer.

Get emergency medical help if you have any signs of an allergic reaction to omalizumab:

Call your doctor at once if you have:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Warnings

Some people using this injection have had a severe, life-threatening allergic reaction either right after the injection or hours later. Allergic reactions may occur even after using this injection regularly for a year or longer.

Get emergency medical help if you have any signs of an allergic reaction to omalizumab: hives, rash; anxiety or fear; flushing (warmth, redness, or tingly feeling); feeling like you might pass out; chest tightness, wheezing, feeling short of breath, difficult breathing; fast or weak heartbeats; swelling of your face, lips, tongue, or throat.

Asthma is often treated with a combination of different drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice.

If you also use an oral steroid medication, do not stop using the steroid suddenly or you may have unpleasant withdrawal symptoms. Talk with your doctor if any of your asthma medications do not seem to work as well in treating or preventing attacks. Your symptoms may not improve right away once you start receiving omalizumab. For best results, keep receiving the injection as directed. Talk with your doctor if your symptoms do not improve after a few weeks of treatment.

Omalizumab should not be used for the emergency treatment of allergic reactions, including anaphylaxis. It is only used in food allergy to reduce the risk of allergic reactions.

Use omalizumab regularly to get the most benefit. Get your prescription refilled before you run out of medicine completely.

Before taking this medicine

You should not use this medicine if you are allergic to omalizumab, or any of the inactive ingredients.  See the bottom of this document for a full list of ingredients. To make sure omalizumab is safe for you, tell your doctor if you have:

Using this injection may increase your risk of certain types of cancers of the breast, skin, prostate, or salivary gland. Talk to your doctor about your individual risk.

While you are using this medicine, you may also have an increased risk of becoming infected with parasites (worms) if you live in or travel to areas where such infections are common. Talk with your doctor about what to look for and how to treat this condition.

Pregnancy

Tell your doctor if you are pregnant or plan to become pregnant during treatment.   If you become pregnant while using this injection, call your doctor.

If you are pregnant, your name may be listed on a pregnancy registry. This is to track the outcome of the pregnancy and to evaluate any effects of omalizumab on the baby.

Breastfeeding 

It is not known whether omalizumab could harm a nursing baby. Tell your doctor if you are breastfeeding or planning to breastfeed a baby..

How should I use omalizumab?

Before you start treatment with this medicine, your doctor may perform an allergy skin test or blood test to make sure this medicine is right for you.

Omalizumabis given as an injection under the skin (subcutaneous injection). When you first start your treatment, the injection will be given to you by your healthcare provider. 

You will be watched closely for a short time after receiving the injection to make sure you do not have an allergic reaction to the medication.

Your healthcare provider may decide that the injections can be administered by you or a caregiver, and you will receive training on the right way to prepare and inject this medicine. Do not try to inject omalizumab until you have been shown the right way to use the prefilled syringe injections.

For children 12 years of age and older, the prefilled syringe may be self-injected under adult supervision. For children 6 to 11 years of age, the prefilled syringe should be injected by a caregiver.

Omalizumab is usually given every 2 or 4 weeks, depending on what condition you are treating.

Your condition may be treated with a combination of drugs. Use all medications as directed by your doctor. Read the medication guide or patient instructions provided with each medication. Do not change your doses or medication schedule without your doctor's advice.

If you also use a steroid medicine, do not stop using it suddenly, or you may have unpleasant withdrawal symptoms. Talk with your doctor if any of your asthma medications do not seem to work as well in treating or preventing attacks.

While using this medicine, you may need frequent medical tests, such as allergy tests and lung function tests. Your stools may also need to be checked for parasites, especially if you travel.

Your condition may not improve right away. For best results, keep receiving the medication as directed. Talk with your doctor if your symptoms do not improve after a few weeks of treatment.

Omalizumab Prefilled Syringe instructions:

For more instructions, including diagrams for all Xolair device types and how to inject, see Xolair Instructions For Use.

Omalizumab dosing information

Usual omalizumab dose for food allergy (IgE-Mediated):

Dose: 75 mg to 600 mg subcutaneously every 2 or 4 weeks.

Usual adult and pediatric dose for asthma:

Dose: 75 mg to 375 mg by subcutaneous injection every 2 or 4 weeks. Dose and frequency of injection is based on weight and pre-treatment IgE levels. 

Comments: 

Use: Management of moderate to severe persistent asthma in patients  (12 Years and Older) who are inadequately controlled with inhaled corticosteroids and with a positive skin test or in vitro reactivity to a perennial aeroallergen.

Usual Adult Dose for Chronic Rhinosinusitis with Nasal Polyps (CRSwNP)

Dose: 75 mg to 600 mg by subcutaneous injection every 2 or 4 weeks. The dose and frequency of injection are based on weight and pre-treatment IgE levels. Click on the link below "Detailed Xolair dosage information" for dose details.

Comments:

Use: As an add-on maintenance treatment for Chronic rhinosinusitis with nasal polyps (CRSwNP) in adult patients 18 years of age and older with inadequate response to nasal corticosteroids.

Usual Adult Dose for Chronic Spontaneous Urticaria (CSU):

Dose: 150mg or 300 mg subcutaneously every 4 weeks.

Comments:

Use: Chronic idiopathic urticaria in patients remaining symptomatic after H1 antihistamine treatment.. 

Xolair formulations

Xolair Autoinjector (single-dose prefilled): 75 mg/0.5 mL, 150 mg/mL and 300 mg/2 mL

Prefilled syringe (single-dose): 75 mg/0.5 mL, 150 mg/mL, and 300 mg/2 mL

Single-dose vial for reconstitution: 150 mg lyophilized powder

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your injection.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What other drugs will affect omalizumab?

Other drugs may interact with this medicine including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your healthcare providers about all medicines you use now and any medicine you start or stop using.
It is important to tell your doctor or healthcare provider if you have any of the following: allergy shots (a series of injections given regularly to prevent the body from developing allergic reactions to specific substances) and medications that suppress your immune system. Your doctor may need to change the doses of your medications or monitor you carefully for side effects.

This list is not complete. Many other drugs may interact with Xolair, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this medication guide.

Does omalizumab interact with my other drugs?

Enter medications to view a detailed interaction report using our Drug Interaction Checker.

Storage

Ingredients 

Active ingredient: omalizumab

Inactive ingredients:

Xolair Prefilled syringe or autoinjector: L-arginine hydrochloride, L-histidine, L-histidine hydrochloride monohydrate, and polysorbate 20.

Xolair Vial: L-histidine, L-histidine hydrochloride monohydrate, polysorbate 20 and sucrose.

Manufacturer

Manufactured by:

Jointly marketed by:

Omalizumab Biosimilars

Biosimilar and interchangeable products are biological products that are highly similar to and have no clinically meaningful differences from the reference product.

Reference products

These are biological products that have already been approved by the FDA, against which biosimilar products are compared. There is 1 for omalizumab.

Xolair (omalizumab) - Genentech, Inc.
Formulation type Strength
Autoinjector 150 mg/mL
Autoinjector 300 mg/2 mL
Autoinjector 75 mg/0.5 mL
Pre-Filled Syringe 150 mg/mL
Pre-Filled Syringe 300 mg/2 mL
Pre-Filled Syringe 75 mg/0.5 mL
Single-Dose Vial 150 mg

View Xolair information in detail.

Popular FAQ

Is Xolair an immunosuppressant?

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. Continue reading

How long before Xolair starts working?

Free serum IgE levels are decreased within an hour of Xolair administration. However it may take several months for the full effects of Xolair to be seen, although some symptom improvement may be noted after a few weeks. Significant improvements were noted after 4 months in those with allergic asthma, after 3 months in those with chronic urticaria, and after 16 to 20 weeks in those with Ig-E-mediated food allergies. Continue reading

How does Xolair work?

Xolair works by preventing IgE from binding to IgE receptors on mast cells and basophils. This prevents mast cells and basophils from releasing histamine and heparin. Histamine narrows smooth muscle in the airways making it harder to breathe and also causes tissue swelling, itchy skin, hives, and other allergic-type symptoms. Heparin makes it harder for blood to clot. Continue reading

Does Xolair cause weight gain?

There were no reports of weight gain or weight loss in clinical trials with Xolair. Weight gain is more likely to be caused by corticosteroids, hydroxyzine, or antihistamines that may also be used to treat allergic asthma or hives. Continue reading

What is omalizumab's mechanism of action?

The omalizumab mechanism of action is designed to target IgE (immunoglobulin E), an antibody produced by the immune system. It works by inhibiting the binding of the IgE antibody to IgE receptors on cells that can lead to inflammation and worsened allergic symptoms. Continue reading

Can Xolair be self-administered at home?

Yes, you or your caregiver can learn how to give Xolair at home if you and your doctor agree that self-injection is appropriate. For children 12 years of age and older, the Xolair prefilled syringe or autoinjector may be self-injected under adult supervision. For children 1 to 11 years of age, only the Xolair prefilled syringe should be used and injected by a caregiver, as the autoinjector is not intended for this age group. Continue reading

Omalizumab and Covid-19 vaccine, what should I know?

If you are being treated with omalizumab, you can be vaccinated with the COVID-19 vaccination at any time, but the ACAAI (American College of Allergy, Asthma, and Immunology) recommends that the COVID-19 vaccine and omalizumab not be given on the same day since, if a reaction or a side effect occurs, it may be challenging to work out which injection was to blame. The ACAAI suggests separating the COVID-19 vaccination and omalizumab by at least 24 hours. There is no reason to stop omalizumab until you complete the course of the COVID-19 vaccinations. Continue reading

What is Xolair approved for?

Xolair (generic name: omalizumab) is approved to treat asthma triggered by allergies, sinus inflammation with nasal polyps, chronic hives and to help reduce allergic reactions due to accidental exposure to certain foods (along with avoiding foods to which you are allergic). It is not used for the emergency treatment of allergic reactions, including anaphylaxis. Continue reading

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.