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Xolair: 7 things you should know

Medically reviewed by Carmen Fookes, BPharm. Last updated on April 29, 2022.

1. How it works

  • Xolair is a brand (trade) name for omalizumab which is an antibody that may be used to treat asthma, urticaria, nasal polyps, and some other conditions.
  • Xolair (omalizumab) works by preventing IgE from binding to IgE receptors on mast cells and basophils. By inhibiting the binding of IgE to the IgE receptor, Xolair prevents the release of histamine and heparin and also reduces the number of IgE receptors on basophils. Histamine is a chemical that has many inflammatory effects on the body. It contracts the smooth muscle tissue in the lungs, uterus, and stomach; dilates blood vessels causing an increase in permeability and a lowering of blood pressure; stimulates the secretion of gastric acid in the stomach; and speeds up the heart rate. Histamine also causes symptoms such as a runny nose, watery eyes, tissue swelling, itchy skin, and hives. Because histamine contracts the breathing tubes it can cause wheezing or make it harder to breathe. Histamine is also one of the main chemicals involved in anaphylaxis, a severe and often fatal allergic response to a previously encountered allergen. Heparin is an anticoagulant that slows the formation of blood clots.
  • Xolair belongs to the class of medicines known as selective immunosuppressants.

2. Upsides

  • May be used to treat allergic asthma that is moderate to severe, persistent, and not adequately controlled by inhaled corticosteroids that occurs in adults and children aged 6 and over who have had a positive skin test to an allergen or who react to an allergen that is present in their environment year-round.
  • May also be used to treat chronic idiopathic urticaria (CIU) (hives) in adults and children aged 12 and older who have already tried antihistamines without success. 93% of people with moderate-to-severe chronic urticaria have increased total IgE levels. Not approved for other forms of urticaria.
  • Approved for nasal polyps in adults aged 18 years and older.
  • Administered by injection under the skin (subcutaneously) once every two to four weeks.
  • Can be self-administered by people with no prior history of anaphylaxis and who have been observed for 3 injections by a healthcare provider. Appropriate training must be provided.
  • Acts on the allergic arm of the immune system, and does not appear to compromise the immune system like traditional immunosuppressants, such as prednisone and cyclosporine.
  • Not associated with an increased risk of infection nor an increase in the risk for COVID-19.
  • Has not been associated with weight gain or loss in clinical trials with Xolair. Weight gain is more likely to be caused by corticosteroids, hydroxyzine, or antihistamines that may also be used to treat allergic asthma or hives.
  • Well tolerated with few interactions.
  • Available as a pre-filled syringe as a 75mg and 150mg dose.

3. Downsides

If you are between the ages of 18 and 60, take no other medication or have no other medical conditions, side effects you are more likely to experience include:

  • Pain (including arm, joint, and leg pain), dizziness, fatigue, headache, injection site reactions, abdominal pain, dermatitis/rash, nasopharyngitis, and earache. Hair loss and severe thrombocytopenia have been reported.
  • Anaphylaxis has occurred following administration of Xolair as early as after the first dose or beyond one year. Symptoms may include bronchospasm, urticaria, or angioedema. Observe patients for an appropriate period after administration of Xolair.
  • The dosage of Xolair for asthma and nasal polyps is based on body weight and serum total IgE levels measured before the start of treatment. The dosage of Xolair for CIU is not dependent on serum IgE or body weight. refer to the tables in the product information for actual dosage recommendations.
  • Associated with a higher risk of cancer of the breast, skin, prostate, and parotid gland (incidence of 0.5% compared to 0.2% in those taking placebo).
  • Corticosteroids should not be abruptly stopped in patients taking Xolair. Instead, discontinue slowly under medical supervision. Churg-Strauss syndrome has been associated with a reduction in corticosteroid treatment. Symptoms include rash, worsening pulmonary symptoms, cardiac effects, or neuropathy.
  • Has been associated with a constellation of symptoms that include arthritis or joint pain, rash, fever, and lymphadenopathy with an onset one to five days after a Xolair dose. Discontinue Xolair if this occurs.
  • Does not treat an acute asthma attack or status asthmaticus.
  • Once discontinued, Xolair may persist in the body for 6 months to one year.
  • When restarting Xolair, base dose on serum gE levels obtained at the initial dose determination if interruptions have lasted less than one year. For interruptions of one year or more, retest total serum IgE levels and base dose on these and the patient's age.
  • Parasitic infections (such as roundworm, hookworm, whipworm, and threadworm) are 0.88 to 4.36 times more likely in people taking Xolair than in those taking a placebo. Monitor patients for these types of infections while they are taking Xolair.
  • Carries a potential for immunogenicity. Antibodies to Xolair were detected in < 0.1% of people treated with Xolair for asthma.
  • There is not enough data to assess the risks of Xolair to the mother or unborn child during pregnancy. Weigh up risks versus benefits.
  • The needle cap of the prefilled syringe contains latex which may cause an allergic reaction in latex-sensitive people.

Note: In general, seniors or children, people with certain medical conditions (such as liver or kidney problems, heart disease, diabetes, seizures) or people who take other medications are more at risk of developing a wider range of side effects. View complete list of side effects

4. Bottom Line

Xolair is an injectable preparation that works by preventing IgE from binding to IgE receptors on mast cells and basophils and may be used to treat allergic asthma, nasal polyps, and chronic idiopathic urticaria. It is administered under the skin once every two to four weeks depending on the condition and is usually well tolerated. Xolair has few interactions.

5. Tips

  • Keep your scheduled appointments with your healthcare provider for your Xolair injection unless you have been taught how to self administer your Xolair.
  • Seek urgent medical attention if you experience shortness of breath, or facial or throat tightness after administering Xolair. If you feel unwell, or experience other signs of infection, tell your doctor immediately. Also remember to tell your doctor about any other side effects that you may be experiencing, such as pain, rash, shortness of breath, or dizziness. Anaphylaxis has been reported with Xolair up to 4 days after administration.
  • Has been associated with a constellation of symptoms that include arthritis or joint pain, rash, fever, and lymphadenopathy with an onset one to five days after a Xolair dose. See your doctor urgently if these occur.
  • The risk of parasitic infections (such as roundworm, hookworm, whipworm, and threadworm) is higher in people taking Xolair compared with those not taking it. Monitor for signs of a worm infection (itchy bottom, weight loss) and seek treatment if one is suspected.
  • Xolair is not recommended during pregnancy unless the benefits outweigh the risks but tell your doctor immediately if you become pregnant while being administered Xolair. Xolair has been administered to breastfeeding women with no obvious increase in adverse effects.

6. Response and effectiveness

  • Forms stable Xolair/IgE complexes which are more slowly excreted from the body than free IgE. This means that total serum IgE levels (bound and unbound) will show an increase in laboratory testing; however, free IgE levels are decreased within an hour of injection, and decreases of greater than 96% have been reported.
  • Free serum IgE levels are decreased within an hour of Xolair administration. However, it may take several months for the full effects of Xolair to be seen, although some symptom improvement may be noted after a few weeks.
  • Trials using Xolair in people with allergic asthma noted significant improvements after 4 months.
  • Trials using Xolair in people with chronic urticaria noted significant improvements after 3 months.
  • Xolair is given every two to four weeks and it can take approximately 7 to 8 days for peak concentrations to be reached after a single injection.
  • Total IgE levels are elevated during treatment and remain elevated for up to one year after discontinuing treatment. This means that retesting of IgE levels cannot be used as a guide for dose determination.

7. Interactions

Medicines that interact with Xolair may either decrease its effect, affect how long it works for, increase side effects, or have less of an effect when taken with Xolair. An interaction between two medications does not always mean that you must stop taking one of the medications; however, sometimes it does. Speak to your doctor about how drug interactions should be managed.

There are few reported interactions with Xolair and most interactions are considered mild or not clinically significant. The following medicines or supplements are reported in the product information as interacting with Xolair:

  • herbals, such as cat's claw or echinacea
  • omacetaxine
  • vitamin e
  • zinc.

You should refer to the prescribing information for Xolair for a complete list of interactions.


Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use Xolair only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2022 Revision date: April 29, 2022.