What Is Xolair?

Xolair is the brand name for omalizumab, a biologic medication made by Genentech and Novartis. It belongs to a class of drugs called monoclonal antibodies — lab-made proteins designed to target specific parts of the immune system.

Specifically, Xolair targets immunoglobulin E (IgE), a protein your body produces during allergic reactions. By blocking IgE, Xolair helps reduce the allergic response that drives conditions like asthma, chronic hives, nasal polyps, and food allergies.

Xolair was first approved by the FDA in 2003 for allergic asthma and has since expanded to treat several other conditions. It's not a pill — it's given as an injection under the skin (subcutaneous injection), either at a doctor's office or at home after proper training.

What Is Xolair Used For?

Xolair has four FDA-approved uses as of 2026:

1. Moderate to Severe Allergic Asthma

Xolair is approved for patients 6 years and older with moderate to severe persistent allergic asthma that isn't well controlled with inhaled corticosteroids. Before starting Xolair, patients must have a positive skin test or blood test showing sensitivity to an airborne allergen, and their IgE levels must be within a specific range.

2. Chronic Spontaneous Urticaria (Chronic Hives)

For patients 12 years and older with chronic hives that don't respond to H1 antihistamine treatment. Chronic spontaneous urticaria causes itchy welts that appear for six weeks or longer without a clear trigger.

3. Chronic Rhinosinusitis with Nasal Polyps (CRSwNP)

Approved for adults 18 and older as an add-on treatment for nasal polyps that haven't responded adequately to nasal corticosteroids.

4. IgE-Mediated Food Allergy

The newest indication, approved in February 2024, for patients 1 year and older. Xolair reduces the risk of allergic reactions from accidental exposure to food allergens. It does not eliminate food allergies — patients must continue avoiding their trigger foods.

This food allergy approval was a major milestone, as Xolair became the first FDA-approved medication to reduce allergic reactions to multiple foods simultaneously.

How Is Xolair Given?

Xolair is administered as a subcutaneous injection (a shot under the skin). It's available in three forms:

• Prefilled syringe (75 mg/0.5 mL or 150 mg/1 mL)
• Prefilled autoinjector (75 mg/0.5 mL or 150 mg/1 mL)
• Lyophilized powder vial (150 mg — mixed by a healthcare professional before injection)

Common injection sites include the thigh, abdomen (away from the belly button), or the outer upper arm. Some doses require multiple injections at different sites.

Where Do You Get Injections?

Because of the risk of anaphylaxis, your first several Xolair injections must be given in a healthcare setting where you can be monitored. After your doctor determines it's safe, you may be trained to self-inject at home.

Xolair Dosage

Xolair dosing depends on your condition, body weight, and IgE levels:

For Asthma, Nasal Polyps, and Food Allergies

Doses range from 75 mg to 375 mg, given every 2 or 4 weeks. Your doctor calculates the exact dose based on your body weight and serum IgE level measured before starting treatment.

For Chronic Hives (CSU)

The dose is simpler: 150 mg or 300 mg every 4 weeks, regardless of IgE level or body weight. Most patients start at 150 mg, and the dose may be increased to 300 mg if needed.

Your doctor will determine the right dose for you. Don't change your dose or frequency without medical guidance.

How Well Does Xolair Work?

Clinical studies have shown significant benefits across all approved uses:

• Asthma: Reduced asthma attacks by approximately 25-50% in clinical trials and decreased the need for rescue inhalers
• Chronic hives: Many patients experienced complete or near-complete clearing of hives within 12-24 weeks
• Nasal polyps: Reduced polyp size and improved nasal congestion symptoms
• Food allergies: In trials, patients could tolerate significantly more of their trigger food after treatment, reducing the risk of severe reactions from accidental exposure

Results vary from person to person. Some patients notice improvement within a few weeks, while others may take several months to see the full benefit.

Important Safety Information

Boxed Warning: Anaphylaxis

Xolair carries an FDA boxed warning (the most serious type of warning) for anaphylaxis. This severe allergic reaction can occur after any injection — including the first — and may be delayed by hours or days. Patients must carry injectable epinephrine at all times.

Other Serious Risks

• Slightly higher cancer rates observed in clinical trials (causal link unclear)
• Eosinophilic conditions including Churg-Strauss syndrome
• Serum sickness-like reactions
• Increased risk of parasitic infections

For a complete breakdown, read our Xolair side effects guide.

Who Should Not Take Xolair?

• Anyone with a known allergy to omalizumab or its ingredients
• Xolair should not be used for acute asthma attacks or emergency allergic reactions
• The needle cap contains natural rubber latex — use caution if you have a latex allergy

How Much Does Xolair Cost?

Xolair is expensive. The cash price ranges from $1,500 to $4,000+ per injection, and annual costs can exceed $30,000 to $50,000 depending on your dose and frequency.

However, most patients don't pay full price. Options to reduce costs include:

• Insurance: Typically covered by commercial insurance and Medicare (Part B for in-office injections, Part D for home use). Prior authorization is usually required.
• Genentech Co-pay Program: Can reduce out-of-pocket costs to as low as $0 for eligible commercially insured patients.
• Genentech Patient Foundation: Provides free Xolair for qualifying uninsured or underinsured patients.
• Biosimilar option: Omlyclo (omalizumab-igec) was approved in 2025 and may offer savings of 15-30%.

Read our full guide on how to save money on Xolair for more details.

Xolair Availability in 2026

Xolair has experienced intermittent supply issues since the food allergy approval dramatically expanded demand in 2024. Availability may vary by region and dosage form.

If you're having trouble finding Xolair, use MedFinder to check pharmacy stock near you, or read our guide on how to check if a pharmacy has Xolair in stock.

Final Thoughts

Xolair is a powerful biologic that has transformed the treatment of severe allergic conditions. Whether you're dealing with asthma, chronic hives, nasal polyps, or food allergies, Xolair offers a targeted approach that goes beyond traditional medications.

Talk to your doctor — specifically an allergist, pulmonologist, or appropriate specialist — to find out if Xolair is right for you. And if you want to understand the science behind it, check out our guide on how Xolair works.