Omalizumab

Generic Name: Omalizumab

Brand Names: Xolair

Omalizumab is an anti-IgE biologic for allergic asthma, chronic urticaria, nasal polyps, and food allergies.

RespiratoryDermatologicBiologic

Drug Class

Anti-Immunoglobulin E (Anti-IgE) Monoclonal Antibody (Biologic)

Pregnancy

Category B; animal reproduction studies showed no evidence of fetal harm. However, there are no adequate, well-controlled studies in pregnant women. Monoclonal antibodies cross the placenta, with increasing transfer as pregnancy progresses. Use only if clearly needed. An observational pregnancy registry (EXPECT) showed no increased risk of major congenital anomalies.

Available Forms

75 mg/0.5 mL prefilled syringe, 150 mg/mL prefilled syringe, 150 mg lyophilized powder for reconstitution (for subcutaneous injection)

What It's Used For

Dosage Quick Reference

These are general dosage guidelines. Your doctor will determine the appropriate dose for your specific situation.

Condition	Starting Dose	Maintenance Dose
Moderate-to-Severe Persistent Allergic Asthma (adults/adolescents ≥ 6 years)	75-375 mg SC every 2 or 4 weeks, based on pretreatment serum IgE level and body weight	Same dose on same schedule; dosing determined by IgE-based nomogram
Chronic Idiopathic Urticaria (adults/adolescents ≥ 12 years)	150 mg or 300 mg SC every 4 weeks	150-300 mg SC every 4 weeks; dose is NOT based on IgE level
Nasal Polyps (adults ≥ 18 years, add-on maintenance)	75-600 mg SC every 2 or 4 weeks, based on IgE level and weight	Same dose on same schedule per IgE-based nomogram

Side Effects

Common Side Effects:

Injection site reactions (pain, redness, swelling)
Headache
Viral infections
Upper respiratory tract infections
Sinusitis
Pharyngitis

Serious Side Effects:

Anaphylaxis (can occur at any time during treatment)
Serum sickness-like reactions
Eosinophilic conditions
Arterial thrombotic events (uncertain relationship)

Drug Interactions

Allergen immunotherapy: Omalizumab may be used alongside allergen immunotherapy. Some studies suggest it may reduce anaphylactic reactions to immunotherapy. However, both treatments affect the immune response, so patients should be monitored.
Other biologic immunomodulators (mepolizumab, dupilumab, benralizumab): Safety and efficacy of concurrent biologic therapy have not been established. Combination use is generally not recommended outside of clinical trials.
Live vaccines: While omalizumab is not a broadly immunosuppressive agent, caution is advised. There is no specific contraindication, but follow standard vaccination guidelines.
Corticosteroids (oral and inhaled): Omalizumab may allow gradual corticosteroid dose reduction in asthma, but steroids should not be abruptly discontinued. Taper under medical supervision to avoid adrenal insufficiency or asthma exacerbation.

Additional Information

Omalizumab is a humanized monoclonal antibody that targets immunoglobulin E (IgE), making it effective for moderate-to-severe allergic asthma and chronic spontaneous urticaria. As the first anti-IgE therapy approved, it represents a breakthrough in treating allergic diseases.

Mechanism of Action

Omalizumab works by:

Binding to free IgE in the blood and interstitial fluid
Preventing IgE from attaching to high-affinity IgE receptors (FcεRI) on mast cells and basophils
Reducing surface-bound IgE on mast cells and basophils
Decreasing FcεRI receptor expression over time
Reducing release of allergic mediators (histamine, leukotrienes, prostaglandins)

This cascade of effects results in decreased allergic inflammation and clinical improvement.

Available Formulations

Omalizumab is available as:

Prefilled syringe: 75 mg/0.5 mL, 150 mg/mL
Lyophilized powder for reconstitution: 150 mg vial

Administered subcutaneously, either in healthcare settings or at home after training.

Medical Uses

FDA-Approved Indications:

Moderate-to-severe persistent allergic asthma in patients ≥6 years with positive skin test or in vitro reactivity to perennial aeroallergens inadequately controlled with inhaled corticosteroids
Chronic spontaneous urticaria (chronic idiopathic urticaria) in adults and adolescents ≥12 years who remain symptomatic despite H1 antihistamine treatment
Chronic rhinosinusitis with nasal polyps in adults inadequately controlled with intranasal corticosteroids

Dosing Guidelines

Allergic Asthma:

Dose based on pretreatment serum total IgE level and body weight
Range: 75-375 mg every 2-4 weeks
Maximum: 375 mg every 2 weeks
Consult dosing tables in prescribing information

Chronic Spontaneous Urticaria:

150 mg or 300 mg subcutaneously every 4 weeks
Dosing not dependent on IgE level or body weight
Assess response periodically; discontinue if no improvement after 6 months

Chronic Rhinosinusitis with Nasal Polyps:

Dose based on IgE level and body weight (same as asthma dosing)

Important Safety Information

Black Box Warning:

Anaphylaxis can occur with any dose, even after years of treatment
Observe patients for appropriate time after each injection
Be prepared to treat anaphylaxis
Patients should carry autoinjectable epinephrine

Contraindications:

Severe hypersensitivity reaction to omalizumab

Warnings and Precautions:

Anaphylaxis: Occurs in 0.1-0.2% of patients
Malignancy: Slightly higher rates observed in clinical trials (unclear if related)
Helminth infections: May increase infection risk
Fever, arthralgia, rash (serum sickness-like reactions)
Do not use for acute asthma exacerbations

Drug Interactions

No formal drug interaction studies conducted. As a biologic, omalizumab is not metabolized by cytochrome P450 enzymes.

Immunosuppressants: Theoretical concern for additive immunosuppression
Allergen immunotherapy: Can be used concurrently

Special Populations

Pregnancy: Limited data; use only if benefit outweighs risk
Lactation: Unknown if excreted in milk
Pediatric: Approved for asthma in children ≥6 years; urticaria in ≥12 years
Elderly: No dose adjustment; use with caution

Frequently Asked Questions

Omalizumab carries a black box warning for anaphylaxis, which can occur after any dose — not only the first. Anaphylaxis has been reported as late as 24 hours after injection. For this reason, patients are typically observed in a healthcare setting for a period (usually 30 minutes) after the first several injections, and all patients should carry injectable epinephrine (EpiPen) at all times.

For allergic asthma and nasal polyps, the dose and frequency are determined using a dosing table based on your pretreatment total serum IgE level (IU/mL) and your body weight (kg). For chronic urticaria, dosing is fixed at 150 mg or 300 mg every 4 weeks regardless of IgE level.

Some improvement may be noticed within the first 4 weeks, but it may take 12 to 16 weeks to see the full benefit. Your doctor will typically assess your response after about 12 to 16 weeks of therapy before deciding whether to continue.

Starting in recent years, self-injection with prefilled syringes has been approved for some patients after the initial doses have been administered safely in a healthcare setting. However, because of the anaphylaxis risk, your doctor will determine when home injection is appropriate. You must always have injectable epinephrine available.

Early clinical trials noted a small numerical imbalance in malignancies between omalizumab and placebo groups. However, longer-term observational studies (including the EXCELS study of over 5,000 patients followed for 5 years) did not show an increased cancer risk. The FDA does not consider this a confirmed risk, but it is mentioned in the prescribing information.

Questions to Ask Your Doctor

Consider discussing these topics at your next appointment:

✓Will I need to stay in the office for observation after each injection, and for how long?
✓Do I need to carry an EpiPen at all times while on omalizumab?
✓How will we measure whether omalizumab is working well enough to continue?
✓Can my inhaled corticosteroid dose be reduced once omalizumab takes effect?
✓Is my IgE level within the treatable range for omalizumab dosing?

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Related Health Conditions

This medication is commonly used to treat or manage the following conditions:

Asthma

Asthma, a chronic lung disease, causes airway inflammation and narrowing, resulting in wheezing, coughing, and shortness of breath, triggered by allergens, irritants, infections, or stress.

Learn More

Sinusitis

Sinusitis involves sinus inflammation and blockage due to infections, allergies, or structural issues, causing facial pain, pressure, and congestion, often following colds or triggered by allergens.

Learn More

Medical Disclaimer: This information is for educational purposes only and should not be considered medical advice. Always consult with your healthcare provider before starting, stopping, or changing any medication. Your doctor can provide personalized recommendations based on your specific health condition and medical history.