Xolair (omalizumab) is a brand-name injection that’s prescribed for certain conditions, such as asthma, in adults and some children. As with other drugs, Xolair can cause side effects, such as headache, hair loss, and severe allergic reaction.

For other information about Xolair, including details about its uses, see this article.

Xolair shots can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

These are just a few of the more common side effects reported by people who took Xolair in clinical trials. These side effects can vary depending on your age and which condition the drug is being used to treat.*

More common side effects of Xolair include:

  • pain, such as joint pain
  • dizziness
  • fatigue
  • reactions at the injection site
  • headache†

* For details about the common side effects in children receiving Xolair for asthma, see “Side effects in children” below.
† For more information about this side effect, see “Side effect specifics” below.

Mild side effects can occur with Xolair use. These may vary based on the condition you are using Xolair to treat. This list doesn’t include all possible mild side effects of the drug. For more information, you can refer to Xolair’s prescribing information.

Mild side effects that have been reported in adults and children ages 12 years and older using Xolair to treat asthma include:

  • pain, which may be felt throughout the body, including the joints, arms, and legs
  • fatigue
  • dizziness
  • skin rash
  • itchy skin
  • earache
  • reactions at the injection site
  • headache*
  • mild allergic reaction†

Mild side effects that have been reported in adults receiving Xolair to treat sinusitis (sinus infection) with nasal polyps include:

  • dizziness
  • pain in the joints
  • pain in the upper abdomen
  • reactions at the injection site
  • headache*
  • mild allergic reaction†

Mild side effects that have been reported in adults and children ages 12 years and older using Xolair to treat hives include:

These side effects may be temporary, lasting a few days to weeks. However, if the side effects last longer than that, bother you, or become severe, be sure to talk with your doctor or pharmacist.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while using Xolair and want to tell the FDA about it, visit MedWatch.

* For more information about this side effect, see “Side effect specifics” below.
† A mild allergic reaction may occur. However, a more severe allergic reaction is also possible. Xolair has a boxed warning for severe allergic reaction. This is a serious warning from the FDA. To learn more, see the “Side effect specifics” section below.

Xolair may cause serious side effects. The list below may not include all possible serious side effects of the drug. For more information, you can refer to Xolair’s prescribing information.

Serious side effects that have been reported and their symptoms include:

  • Risk of heart and blood circulation problems, such as blood clots, stroke, and heart attack. Symptoms can include:
    • pain in your chest or one of your legs
    • leg and arm weakness on one side of your body
    • slurred speech or being unable to speak clearly
    • changes in your vision
  • Parasitic worm infection. Symptoms may not always occur, but they can include:
    • diarrhea or vomiting
    • abdominal pain
    • fever
    • slowed growth in children
  • Immune system reaction. Symptoms can include:
  • Bone fractures (breaks).
  • Severe allergic reaction.*†
  • Cancer*

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

* For more details on this side effect, see “Side effect specifics” section below.
† Xolair has a boxed warning for this side effect. This is a serious warning from the Food and Drug Administration (FDA). To learn more, see the “Side effect specifics” section below.

Doctors prescribe Xolair to treat a certain form of asthma in children ages 6 years and older, among other uses.

The following side effects were commonly reported in children ages 6 to 11 years who took Xolair for asthma:

If you’re concerned about the side effects your child may experience during Xolair treatment, talk with their doctor. They can recommend ways to avoid or help ease your child’s side effects.

Xolair may cause several side effects. Here are some frequently asked questions about the drug’s side effects and their answers.

Are there any long-term side effects of Xolair?

Xolair’s more common side effects are usually temporary. For example, if you have injection site reactions, they should go away within a few days.

However, some of the rare, serious side effects of Xolair may have long-term consequences. For example, it’s possible to develop cancer or have bone fractures (breaks) during Xolair treatment. These conditions can affect a person for a long time, even after they stop Xolair treatment.

If you experience side effects that do not go away or ease with time, your doctor can recommend ways to relieve them. If these side effects do not ease or go away, or you cannot tolerate them, your doctor can discuss other possible treatment options with you.

Does Xolair treatment cause weight gain or weight loss as a side effect?

No. Clinical trials did not report changes in body weight as a side effect of Xolair.

However, your doctor will determine your Xolair dosage based on body weight, among other factors. If you lose or gain weight while you’re using Xolair, tell your doctor. They may need to adjust your dose to ensure you receive the right amount for your weight. (For details about Xolair’s dosage, see this article.)

If you experience weight changes during Xolair treatment, your doctor can try to identify the cause. They can also recommend ways to maintain a weight that’s healthy for you.

What side effects should I expect with Xolair injections for hives?

The side effects of Xolair can vary depending on which condition the drug is being used to treat. In clinical trials, the following side effects were common in people receiving Xolair for hives:

Other side effects may also occur. If you have concerns about your risk of side effects while using Xolair for hives, talk with your doctor. They may recommend ways to help prevent or manage side effects.

Does stopping Xolair treatment cause withdrawal symptoms?

No. Stopping Xolair treatment is not known to cause withdrawal symptoms. Symptoms of withdrawal can occur when you stop taking certain medications that your body has become dependent on. When your body is dependent on a drug, you need to continue taking that drug to function as you typically would.

Keep in mind that the symptoms of your condition may return if you stop using Xolair. Talk with your doctor if you’d like to stop receiving Xolair. In some cases, you may need to stop Xolair treatment. Your doctor will recommend the best time to do so and explain what you may expect when treatment ends.

Is depression a side effect of Xolair?

Depression was not reported as a side effect in clinical trials of Xolair. However, some of Xolair’s side effects, such as fatigue and pain, may cause a depressed mood.

Sinusitis with nasal polyps, asthma, and hives can be chronic (long-term) conditions. The ongoing nature of these conditions and their symptoms may be associated with feelings of depression or low mood in some people.

Talk with your doctor if you’re feeling depressed. They can determine whether your condition or treatment side effects are causing your depressed mood. If you need additional support, they can also recommend healthcare professionals who specialize in treating depression.

Learn more about some of the side effects that Xolair may cause. To find out how often side effects occurred in clinical trials, see the prescribing information for Xolair.

Allergic reaction, which may be severe

Xolair can cause a mild allergic reaction or a severe allergic reaction called anaphylaxis. The drug has a boxed warning for anaphylaxis. This is a serious warning from the Food and Drug Administration (FDA). A boxed warning alerts doctors and patients about drug effects that may be dangerous.

Anaphylaxis is a life threatening reaction. It can occur right after your dose of Xolair or days after your dose. It can also occur on your first dose of Xolair or after you’ve been using the drug for a while. However, anaphylaxis was rarely seen in clinical trials.

Symptoms of a mild allergic reaction can include:

Symptoms of a severe allergic reaction can include the same symptoms as above, as well as:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe
  • trouble breathing
  • low blood pressure
  • shock (a life threatening reaction that causes reduced blood circulation to your organs)
  • loss of consciousness

What you can do

Before your doctor prescribes Xolair, they’ll discuss the risk of severe allergic reaction. Be sure to tell them if you have any allergies to food or medications.

If your doctor determines Xolair is safe for you, they’ll give your dose of Xolair at their office or a clinic. This will allow them to monitor you for an allergic reaction following your dose. If you have a reaction, they can treat it at that time.

If after you leave your doctor’s office you have mild symptoms of an allergic reaction, call your doctor right away. They may recommend ways to ease your symptoms and determine whether you should keep using Xolair. However, if your symptoms are serious and you think you’re having a medical emergency, immediately call 911 or your local emergency number.

If your doctor determines that it’s unlikely you’ll have a reaction to Xolair, they may recommend you self-inject Xolair doses at home. However, if you experience an allergic reaction at home, be sure to call your doctor or seek emergency help if needed.

Hair loss

Hair loss may occur with Xolair treatment. Clinical trials of Xolair rarely reported this as a side effect in people using Xolair for hives. In clinical trials, hair loss wasn’t seen in people using Xolair for asthma or sinusitis with nasal polyps.

What you can do

If you’re concerned about hair loss, talk with your doctor before starting Xolair treatment. They can discuss your risk of this side effect and recommend alternative treatments if needed.

Cancer

Some people receiving Xolair have developed cancer during treatment with Xolair. This side effect was very rare in clinical trials of Xolair.

In trials, some adults and children ages 12 years and older developed breast cancer, prostate cancer, or skin cancer. However, more research is needed to determine whether the cancer was caused by Xolair. New cancer development was not reported in children ages 6 to 12 years who were receiving Xolair.

Symptoms can include:

What you can do

Talk with your doctor about your personal and family history of cancer. They’ll discuss your risk of cancer before starting Xolair treatment. If you and your doctor decide that Xolair is safe for you, your doctor can advise you on specific cancer symptoms to watch for.

Headache

Headache may occur while using Xolair. Headache was one of the common, mild side effects reported in Xolair clinical trials. This side effect was reported in people using Xolair for sinusitis with nasal polyps, hives, and asthma.

What you can do

Talk with your doctor if you experience headaches during Xolair treatment. They may recommend over-the-counter medications to provide relief.

This drug comes with several warnings.

Boxed warning: Severe allergic reaction

This drug has a boxed warning for risk of severe allergic reaction. This is a serious warning from the Food and Drug Administration (FDA). For details, see the “Side effect specifics” section above.

Other precautions

Be sure to talk with your doctor about your health history before you start Xolair treatment. This drug may not be the right treatment option for you if you have certain medical conditions or other factors that affect your health. These are known as drug-condition or drug-factor interactions. The conditions and factors to consider include:

Sudden asthma symptoms. Xolair should not be used to treat sudden symptoms of asthma or asthma attacks (flare-ups). The drug hasn’t been shown to be effective in treating urgent asthma problems. Tell your doctor if you are having sudden asthma symptoms or flare-ups. They’ll recommend the right drug to take to provide fast relief.

Steroid treatment. Tell your doctor if you’re taking steroid drugs for nasal polyps or asthma. Before starting Xolair treatment, your doctor will likely recommend you slowly stop taking steroids instead of suddenly stopping them. Your doctor will advise the best way for you to end the steroid treatment.

Parasitic infection. Xolair may increase the risk of parasitic worm infections in people who have a higher risk of these infections. Let your doctor know if you’ve had a parasitic infection or have been to places where they occur. They can test your stool to determine whether you have a parasitic infection and recommend treatment for it, if needed. Talk with your doctor about your risk of these infections before you start Xolair treatment.

Cancer. Xolair may increase the risk of developing cancer or worsening current cancer. Some people receiving Xolair have developed breast, prostate, or skin cancers. Talk with your doctor about your risk of cancer and any family history of cancer.

Allergies to latex. If you have a latex allergy, you should not use the prefilled syringes of Xolair. The prefilled syringes have a cap that contains latex. Tell your doctor if you have a latex allergy before starting Xolair. They’ll prescribe one of the other forms of Xolair, which do not contain latex.

Pregnancy. It’s unknown whether Xolair is safe to use during pregnancy. See “Pregnancy and breastfeeding while taking Xolair” below for more details.

Breastfeeding. It’s not known whether Xolair is safe to use while you’re breastfeeding. For more information, view “Pregnancy and breastfeeding while taking Xolair” below.

Severe allergic reaction. If you’ve had a severe allergic reaction to Xolair or any of its ingredients, your doctor will likely not prescribe Xolair. If you’re not sure whether you’ve had a severe allergic reaction to this medication in the past, talk with your doctor before starting treatment.

Alcohol with Xolair

There aren’t any known interactions between alcohol and Xolair. However, you should discuss with your doctor whether drinking alcohol during Xolair treatment is safe for you.

Alcohol can affect your body in many ways that may in turn affect your health. For example, alcohol can weaken your immune system. This can lead to an increased risk of cancer or infection. Alcohol can also cause dizziness, which is a side effect of Xolair. Drinking alcohol while using Xolair may increase the risk or severity of this side effect.

If you drink alcohol, talk with your doctor about whether it’s safe for you to drink it during treatment with Xolair.

Pregnancy and breastfeeding while taking Xolair

Below is information about using Xolair during pregnancy or while breastfeeding.

Pregnancy

It’s not known whether Xolair is safe to use during pregnancy. This drug crosses through the placenta during pregnancy. (The placenta is the organ that passes nutrients to a developing fetus.) So if a person uses the drug during pregnancy, the fetus is likely to be exposed to Xolair.

Researchers studied Xolair’s safety during pregnancy in a study involving 250 pregnant females* with asthma. Most of the people in this group took Xolair during the first trimester (first 3 months) and at least half took Xolair for nearly 9 months.

The study reported no increase in pregnancy loss or congenital anomalies (also known as birth defects). This was in comparison with a group of pregnant females with asthma who did not receive Xolair during pregnancy.

However, more infants were born with low birth weight to females who took Xolair compared with those who did not. This may be due to those in the Xolair group having more severe asthma. Asthma that’s not managed can lead to pregnancy-related problems, such as low birth weight or premature birth. More studies are needed to know for sure.

If you are pregnant or are planning a pregnancy, talk with your doctor about whether it is safe to start or continue receiving Xolair.

* Sex and gender exist on spectrums. Use of the term “female” in this article refers to sex assigned at birth.

Breastfeeding

It’s not known whether Xolair passes into breast milk or whether it affects the ability to produce breast milk.

A study that assessed Xolair’s safety during pregnancy also monitored the child’s health after birth. Most of these children were breastfed by people who were receiving Xolair. The study found no difference in the frequency of harmful outcomes or side effects in these children. This was compared with children who were breastfed by people not receiving Xolair.

Talk with your doctor to learn the risks and benefits of breastfeeding during Xolair treatment.

The most common side effects of Xolair are mild. However, the drug can cause serious side effects in rare cases. Contact your doctor if you have side effects that are bothersome or serious. For more information, see “Side effect specifics” above.

If you’d like to learn more about Xolair, talk with your doctor or pharmacist. They can answer any questions you have about side effects of the drug.

Besides talking with your doctor, you can do some research on your own. These articles might help:

Disclaimer: Medical News Today 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.