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What is omalizumab used for?

Omalizumab can be used for when urticaria will not go away.

Chronic urticaria is itchy hives or a nettle-sting like rash that lasts 6 weeks or more. There is no known cause.

Treatments for this include antihistamines (such as cetirizine, loratadine, fexofenadine) and, sometimes leukotriene antagonist therapy (such as Montelukast).

Children over the age of 12 years who have not responded to standard treatment may be offered omalizumab.

How does it work?

Omalizumab is an antibody that works by binding to all different types of allergy (called IgE) antibodies in the blood.

It stops the antibody from attaching to some cells, which stops them from releasing too much histamine and other inflammatory substances which cause the urticarial rash.

How is omalizumab given?

Omalizumab (also known by brand name Xolair®) is given as an injection into the tissue under the skin, usually in the upper arm.

For urticaria, this is given as 2 pre-filled 150 mg injections, every 4 weeks.

Illustration of how to inject someone


Response to treatment varies. It may take anywhere between 1 to 4 months to notice any improvement in symptoms.

Children will be assessed after the 4 dose to see if it is beneficial.

If the symptoms have not improved, then the medication is unlikely to work and will be stopped.

If there is a clear benefit, the injections will be continued for another 2 months before being stopped.

The omalizumab injections may be restarted if symptoms return in 6 monthly blocks.

Side effects and risks

Like all medications, omalizumab can cause side effects.

The most common side effects include:

  • injection site reactions (swelling, redness, pain, warmth, itching)
  • dizziness
  • respiratory infections such as cold or sinusitis
  • joint pain
  • rash
  • headache

These can happen in up to 1 in 10 children and are usually mild.

Less common side effects happen in up to 1 in 100 people and include:

  • flu-like symptoms, sore throat, cough
  • feeling sleepy or tired
  • tingling or numbness of hands or feet
  • feeling sick or being sick, indigestion, diarrhoea, tummy pain
  • fainting, light headedness, flushing
  • itching, hives, rash, swelling

Rare side effects happen in less than 1 in 1000 people and can include:

  • Serious allergic reaction or anaphylaxis. This usually happens within 1 to 2 hours of the first or following injections. Symptoms include sudden tongue swelling, throat or chest tightening, shortness of breath, wheezing or trouble breathing, dizziness, light-headedness, confusion, collapsing and losing consciousness.
  • Auto-immune conditions such as systemic lupus erythematosus (SLE). Symptoms include muscle pain, joint pain and swelling, rash, fever, weight loss, and fatigue.

There is also an increased risk of a parasitic or worm infection, so please contact the team if you are planning to travel.

It is very important to make the team aware if there any chance of your child being pregnant.

Your doctor will discuss the side effects and you will have a chance to ask questions before signing a consent form.

Preparation and procedure

  • If your child has asthma, it is important that this is well-controlled on the day of the injections. Please continue to use the preventer medicines.
  • Please contact the team in advance if there has been any recent illness or worsening of asthma.
  • Please also continue to use any other regular medications such as antihistamines.
  • Please bring the weekly urticaria activity score sheet (UAS7) and quality of life questionnaire (CU-Q2OL).
  • The injections are quick but may be a little painful or uncomfortable. If you would prefer to use a numbing cream or cold spray, please let the team know.
  • Your child will be observed for 2 hours after the first injection to make sure there are no immediate severe reactions. For subsequent injections, the observation period will be between 30 to 60 minutes.
  • You may have to stay longer if there are any signs of an allergic reaction.

Contact us

If you have any questions or concerns, please contact:

  • Allergy nurses on 0114 226 7872
  • Allergy secretaries on 0114 271 7585
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Please note: this is a generic information sheet relating to care at Sheffield Children’s NHS FT. These details may not reflect treatment at other hospitals. This information is not intended as a substitute for professional medical care. Always follow your healthcare professionals’ instructions. If this resource relates to medicines, please read it alongside the medicine manufacturer’s patient information leaflet. If this information has been translated into another language from English, efforts have been made to maintain accuracy, but there may still be some translation errors. If you are unsure about any of the guidance in this resource or have specific questions about how it relates to your child, always ask your healthcare professional for further advice.

Resource number: ALG29

Resource Type: Article

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