Key Takeaways

  • Injection-related side effects (injection site reactions) are among the most common side effects of Xolair. Symptoms include bruising, skin color changes, burning, stinging, itching, pain, and swelling at the injection site. They typically occur within 1 hour of injection and last fewer than 8 days.
  • Common mild side effects include fatigue, headache, joint pain, upper abdominal pain, and infections (such as sinus infections or upper respiratory infections). Most of these side effects are temporary and manageable.
  • The medication has a boxed warning (the FDA’s most serious warning) for a risk of anaphylaxis, which is a severe allergic reaction that can be life threatening. It may occur after the first dose or a year or more after starting treatment.

Specifically, Xolair treats:

Xolair is also used to reduce the risk of a certain type of allergic reaction, including anaphylaxis, from some foods in adults and children ages 1 year and older. For this purpose, Xolair is used along with the avoidance of known foods and food ingredients that trigger allergic reactions.

The active ingredient in Xolair is omalizumab. The drug comes in different forms for injection under your skin.

Keep reading to learn about the common, mild, and serious side effects that Xolair can cause.

The following lists contain some of the more common side effects reported by people who took Xolair in studies. These side effects can vary depending on the condition being treated.

Asthma

More common side effects in people receiving Xolair injections for asthma include:

  • pain, including joint pain and pain in the legs
  • injection-related side effects (also called injection site reactions)
  • fatigue (low energy)
  • dizziness
  • skin rash

Chronic sinusitis with nasal polyps

More common side effects in people receiving Xolair injections for chronic sinusitis with nasal polyps include:

  • headache
  • injection-related side effects
  • joint pain
  • upper abdominal pain
  • dizziness

Hives

More common side effects in people receiving Xolair injections for hives include:

Food allergies

More common side effects reported in children receiving Xolair injections to reduce the risk of reactions to food allergies include:

  • fever
  • injection-related side effects (also called injection site reactions)

For more information about some of these side effects, see the “Tips for managing side effects” section.

Some people may experience mild side effects during Xolair treatment. These side effects may vary depending on the condition Xolair is treating.

Examples of mild side effects reported in people receiving Xolair include the following. See the Xolair prescribing information for details about others.

In most cases, these side effects should be temporary, and some may be managed easily. But if you have any symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop Xolair treatment unless your doctor recommends it.

For more information about some of these side effects, see the “Tips for managing side effects” section.

Xolair may cause serious side effects in some people. Serious side effects reported with Xolair include:

See the Xolair prescribing information for more details.

If you develop serious side effects during Xolair treatment, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, call 911. Or call your local emergency number immediately.

Note: After the FDA approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone. It gives doctors and researchers more information about how the drug works in real life. If you’d like to notify the FDA about a side effect you’ve had with Xolair, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, Xolair can cause a mild or serious allergic reaction. It also can cause a serious allergic reaction known as anaphylaxis. In studies and after the drug became available on the market, anaphylaxis occurred rarely.

It’s important to understand the symptoms of a mild and serious allergic reaction, including anaphylaxis, so you can get help right away if you develop symptoms.

Mild allergic reaction

Symptoms of a mild allergic reaction can include:

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. To manage your symptoms, they may suggest:

  • an over-the-counter (OTC) antihistamine that you swallow, such as Benadryl (diphenhydramine)
  • a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you had a mild allergic reaction to Xolair, they’ll decide whether you should continue receiving it.

Serious allergic reaction, including anaphylaxis

Symptoms of a serious allergic reaction, including anaphylaxis, require immediate medical care. See the “Boxed warning for Xolair” section below for symptoms and what to do if you experience this side effect.

Common side effects that have been reported in children receiving Xolair include:

If you have questions about side effects that your child may experience during Xolair treatment, talk with their doctor.

For more information about some of these side effects, see the “Tips for managing side effects” section below.

Xolair has a boxed warning for the risk of anaphylaxis, which is a severe allergic reaction that can be life threatening. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

If you’ve ever had an allergic reaction to any of the ingredients in Xolair, including latex, you should not receive this medication. Symptoms of anaphylaxis may include:

  • swelling of your mouth, tongue, or throat, which can make it difficult to breathe
  • constriction (tightening) of the airways in your lungs, which can cause:
    • difficulty breathing
    • shortness of breath
    • wheezing or a whistling sound when you inhale
    • coughing
    • pain or tightness in your chest and back
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • low blood pressure
  • hives (itchy welts on the skin)
  • fainting

Due to this risk, your doctor will monitor you after you receive your first injection. This is to ensure that you don’t develop symptoms of anaphylaxis. Some people who experienced anaphylaxis had reactions after their first dose. But, in some cases, anaphylaxis may not occur for a year or more after starting Xolair treatment.

For safety, your doctor may prescribe an EpiPen (epinephrine) for you. You should keep this with you or at home for emergency treatment of an anaphylactic reaction to Xolair.

What to do about an allergic reaction

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms that you had a serious allergic reaction to Xolair, they may recommend switching to a different treatment.

Discuss this side effect with your doctor if you’re concerned about it. They can help you learn more about it.

Learn more about some of the side effects Xolair may cause.

Injection site reaction

Injection-related side effects, also called injection site reactions, were common in studies of Xolair. These occur at the injection site and usually happen within 1 hour of an injection and last for fewer than 8 days.

Most people who experienced these side effects were less likely to have them with continued use of Xolair. So your risk of this side effect may decrease over time.

Examples of injection-related side effects include:

  • bruising
  • redness or other skin color changes
  • burning, stinging, or warmth in your skin
  • itching
  • rash or hives
  • pain
  • swelling

What might help

If you experience injection-related side effects during treatment with Xolair, talk with your doctor or pharmacist. They may be able to recommend ways to ease them.

Upper abdominal pain

In studies, upper abdominal pain was among the most common side effects in:

What might help

If you experience upper abdominal pain during Xolair treatment, talk with your doctor. They may be able to recommend ways to decrease this side effect or recommend treatment options for it.

Fatigue

Fatigue was a common side effect reported in studies of people receiving Xolair injections for asthma. However, fatigue was not reported by people receiving Xolair injections for hives or for chronic sinusitis with nasal polyps.

What might help

If you notice a decrease in your energy levels while receiving Xolair, talk with your doctor or pharmacist. They may be able to determine what’s causing your fatigue and the best way to treat it.

Headache

In studies, headache was one of the most common side effects reported in people receiving Xolair for chronic sinusitis with nasal polyps or hives. Headaches also commonly occurred in children using Xolair for asthma.

Headache was not reported as a side effect of Xolair injections when they were used to reduce or prevent food allergies in studies. But headache is a possible side effect of Xolair when it’s used for any other purpose.

What might help

If you experience headaches that are frequent or bothersome to you, talk with your doctor or pharmacist. They may recommend OTC treatment options, such as Tylenol (acetaminophen), or they may suggest other ways to treat your headaches.

Joint pain (arthralgia)

Joint pain (arthralgia) was a common side effect reported by people receiving Xolair in studies.

In some cases, joint pain can be a symptom of a more serious condition called serum sickness. This condition usually causes fever and rash along with joint pain.

What might help

If you develop joint pain, talk with your doctor. If you develop serum sickness, your doctor will recommend that you stop Xolair treatment. They can discuss other treatment options for your condition.

If your joint pain is not associated with serum sickness, your doctor may recommend OTC pain relievers, such as Tylenol. Or they may suggest other ways to decrease your joint pain.

Keeping track of side effects

During your Xolair treatment, consider keeping notes on any side effects you’re having, so you can share the information with your doctor. This is especially helpful when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of the drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Your doctor can use this information to adjust your treatment plan if necessary.

Can Xolair be dangerous?

Xolair injections are generally safe and effective when used as directed for the indications in the drug’s prescribing information. But certain serious side effects can occur in some people.

For example, Xolair has a boxed warning for anaphylaxis. A boxed warning is the most serious warning from the FDA. To learn about other potentially dangerous side effects of Xolair, see the “Serious side effects of Xolair” section.

If you have concerns about the safety and potential dangers of Xolair injections, talk with your doctor.

Does Xolair cause weight gain or weight loss?

No, you shouldn’t experience weight gain or weight loss during Xolair treatment. Weight changes were not reported by people receiving Xolair in studies.

If you have unexplained weight changes during treatment with Xolair, talk with your doctor. They can try to determine the cause.

Does Xolair cause any long-term side effects?

Yes, it’s possible that Xolair may cause long-term side effects. For example, this medication may raise your risk of heart attack, stroke, or cancer, which can have long-term complications. But these side effects are rare.

Short-term mild side effects are much more common with Xolair than long-term side effects. But if you’re concerned about long-term side effects with this drug, talk with your doctor or pharmacist.

How long do side effects from Xolair typically last?

It depends which side effects you’re experiencing. For example, injection-related side effects usually go away within 8 days after an injection. These side effects become less likely the longer a person uses Xolair.

Other side effects of Xolair, such as joint pain, may last longer, and some may even last throughout Xolair treatment. A doctor or pharmacist may be able to recommend treatment for your side effects.

Can Xolair weaken my immune system and raise my risk of side effects?

Based on how Xolair works, it’s thought that the drug doesn’t weaken your immune system.

Infection can occur during Xolair treatment but keep in mind that people with asthma and chronic sinusitis with nasal polyps (two conditions Xolair is used to treat) have a higher risk of infection.

Xolair is a biologic (a drug made from living cells). Other biologics, including those used to treat autoimmune conditions such as psoriasis and rheumatoid arthritis, work by weakening your immune system. But Xolair works differently to treat asthma, hives, and chronic sinus infection with nasal polyps.

If you have questions about how Xolair could affect your immune system, talk with your doctor or pharmacist.

Before you start treatment with Xolair, talk with your doctor about any other medical conditions you have or other medications you’re taking. They can determine whether Xolair may be a safe treatment option for your condition.

Xolair has a boxed warning for anaphylaxis. A boxed warning is the most serious warning from the FDA.

Xolair can sometimes cause harmful effects in people with certain conditions. This is known as a drug-condition interaction. Other factors may also affect whether Xolair is a suitable treatment option for you.

Discuss your health history with your doctor before starting Xolair treatment. Be sure to tell them if any of the following factors apply to you:

  • difficulty breathing or bronchospasm (tightening of the muscles in your lungs)
  • allergic reaction to any Xolair ingredients, including latex
  • parasitic infection, such as hookworm or roundworm
  • previous cancer
  • currently using steroid medication for asthma or nasal polyps
  • you’re pregnant or breastfeeding or planning to become pregnant or breastfeed

More information and support

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You may also want to check out the online communities at Bezzy. It’s a place where people with certain chronic conditions can find support and connect with others.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

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