How Long Does Xolair Take to Work? Plus, 6 Other FAQs

Xolair (omalizumab) is an injectable medication that can offer relief from chronic conditions associated with allergies when other treatments haven’t worked. But whether you’ve been prescribed Xolair for allergic asthma, chronic hives, or another health condition, you may have several questions about the medication.

Your healthcare team will walk you through the basics, such as how to inject Xolair and what side effects to expect. But how long does Xolair take to work? And does it suppress the immune system? We address these issues and more below with answers to seven frequently asked questions about Xolair.

1. How long does Xolair take to work?

Xolair works by binding to an antibody called immunoglobulin E (IgE). IgE is a key driver of allergic reactions and inflammation in the body.

Based on studies, Xolair can start working as soon as 4 weeks (1 month) after starting treatment — and possibly sooner. But it may take as long as 16 weeks (4 months) to feel its full effects. Here’s what studies have shown about the average time it takes for Xolair to start treating specific health conditions:

• Allergic asthma: 4 to 16 weeks

• Chronic rhinosinusitis with nasal polyps (CRSwNP): 4 to 16 weeks

• Chronic hives of unknown cause: 4 (or less) to 12 weeks

• Food allergies: 16 weeks

Your prescriber can talk to you about when you should start to see benefits from Xolair. In addition to setting expectations about timing, they can also let you know what to look for to make sure it’s working. 

If you’re not feeling the benefits after several months of treatment, your prescriber can determine if you should continue Xolair or switch to a different treatment.

2. Can Xolair be given at home?

Yes, you may be able to administer Xolair injections at home. But the first three doses (sometimes more) need to be given in a healthcare setting. This is because Xolair can cause a severe allergic reaction, or anaphylaxis.

Anaphylaxis after receiving Xolair isn’t common. If this type of reaction does occur, it usually happens within the first three doses, typically within 1 to 2 hours of receiving the medication. That’s why the doses are given in a healthcare setting, where treatment can be given quickly. 

EXPERT PICKS: WHAT TO READ NEXT

• Xolair for food allergies: People with food allergies may accidentally be exposed to allergens. Learn how Xolair (omalizumab) can help lower the risk of having a serious allergic reaction to foods.

• Xolair side effects: Do you experience pain and redness after injecting Xolair? Here are common and rare Xolair side effects and how to manage them.

• How to inject Xolair: Pharmacists break down how to inject Xolair and other tips for taking it.

It is possible to have a reaction later on. So your prescriber will consider your personal risks when determining if you can safely administer Xolair at home.

Before you start injecting Xolair at home, your healthcare team will want to be sure that you’re able to recognize and treat anaphylaxis symptoms. They’ll also show you how to inject Xolair properly. You can give yourself the injections, or they can be done by a family member, friend, or caregiver.

Xolair is injected subcutaneously (under the skin) in the thigh or stomach. The upper arm is also an option if someone else is giving you the injection. Xolair comes in an easy-to-use prefilled syringe or autoinjector. So you won’t need to follow complex mixing instructions like you would with a traditional vial and syringe.

3. Can Xolair make hives worse?

It’s unlikely that the active ingredient in Xolair will make hives worse. In fact, Xolair has been shown to improve chronic hives symptoms, including raised itchy bumps (called wheals), and itching severity.

However, there have been a few reports of people having worsening hives after starting treatment with Xolair. But it’s not clear if Xolair itself was the cause. It’s thought that one of the inactive ingredients in Xolair, namely polysorbate, may have contributed to this effect.

Based on clinical trials, Xolair is generally well tolerated. And people who take Xolair to treat chronic hives usually only experience mild, temporary side effects. These side effects can include injection site reactions, headaches, and fever.

If you are receiving Xolair for chronic hives, talk to your prescriber about what to do if your hives get worse after starting treatment. They may suggest stopping Xolair or recommend other treatments to help manage your symptoms.

4. Is Xolair a steroid?

No, Xolair isn’t a steroid. 

Steroids, also called corticosteroids, are a broad class of medications that treat different health conditions involving inflammation. Steroids can come as oral pills, nasal sprays, and injections, among other dosage forms. They’re often used for health conditions that are also treated by Xolair, such as asthma and CRSwNP. 

Steroids work by mimicking hormones in the body that reduce inflammation. As mentioned, Xolair works by lowering levels of IgE, an antibody produced by the immune system, not mimicking hormones. Because of this, its side effects don’t resemble steroid side effects.

5. Does Xolair suppress the immune system?

Xolair doesn’t appear to meaningfully suppress or weaken the immune system. Xolair targets IgE antibodies, which don’t seem to play a big role in fighting infections. These antibodies are mainly released in response to allergens, such as pollen or certain foods, and are known to worsen conditions such as asthma, hives, and chronic sinus inflammation. This is why Xolair can help with these allergic conditions.

However, there have been reports of parasitic infections in some people taking Xolair who are at higher risk for these infections. IgE may play a role in helping the body fight off parasitic infections. But it’s not clear if Xolair’s effects on IgE actually increases the risk of parasitic infections.

If you’re concerned about Xolair’s effects on the immune system, talk with your prescriber. They can help you understand your specific risks and how to safely use Xolair.

6. Is Xolair a biologic?

Yes, Xolair is a biologic medication. Biologics have many uses, from treating health conditions to preventing certain infections. They come from living sources and are more structurally complex than nonbiologic medications. Biologics most often come as injections or infusions.

Xolair is one of several biologics for asthma and other chronic conditions related to allergies. Biologics like Xolair are typically reserved for situations in which other treatments haven’t worked. They also tend to cost more than other treatment options and have to be filled at specialty pharmacies (as discussed below).

7. Is Xolair a specialty medication?

Yes, Xolair is considered a specialty medication. This means it’s only available at specialty pharmacies. 

Specialty pharmacies are unique because they manage medications that require highly specific handling, storage, and administration. Specialty medications are usually expensive and require prior authorizations for insurance coverage. They’re often shipped or delivered to the home, rather than picked up in person.

If you’re prescribed Xolair, your healthcare team will help connect you with a specialty pharmacy that can fill and deliver your medication.

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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