What is Omalizumab?
Omalizumab (Xolair) is a drug that interferes with natural antibodies called IgEs to prevent them from causing histamine release from certain cells in the body. It can improve urticaria and angioedema as histamine is responsible for hives and swellings.
What is it used for?
It is used to treat chronic urticaria and angioedema that does not respond to the standard treatments e.g. H1 antihistamines (cetirizine, fexofenadine, loratadine), H2 antihistamines (famotidine) and leukotriene antagonist therapy (montelukast).
How is it administered?
Omalizumab is given as two 150mg injections subcutaneously (under the skin) every 4 weeks. It is delivered in an outpatient setting. The injections are very quick but patients stay under observation for 2 hours after the first injection to monitor for signs of an allergic reaction.
Response to omalizumab is assessed at/after the 4th dose (4th month). If there has been no significant improvement, omalizumab is stopped. If urticaria has responded to the treatment, the 6 month course will continue. If the urticaria/angioedema returns after the course, omalizumab can start again. Home therapy (usually after the first 4 months) can be considered.
Are there any side effects?
Side effects of omalizumab are rare. Common side effects include headache, abdominal pain, fever, joint pain (flu like symptoms) and injection site reactions (bruising, swelling, redness, pain, warmth, stinging, itching). Anaphylaxis is a potentially serious allergic reaction which can very rarely occur after the injection. Please inform your medical team if you notice any of the following during or after your injection: itching, rash, swelling of the face, neck, tongue, hands and feet, difficulty in breathing or swallowing, dizziness, an upset stomach, blurred vision, chest pain.
If you are planning to travel to an area with a high risk of parasitic infections please let your doctor know as omalizumab removes IgE that is needed to fight parasitic infections.
For further information about omalizumab, including a complete list of side effects, read the product information sheet which comes with the injections. If you have any questions about omalizumab, please ask your doctor at OneWelbeck.