Omalizumab, sold under the brand name Xolair, is a medication originally designed to reduce sensitivity to allergens. It has been used to try to control severe allergic asthma, which does not respond to high doses of corticosteroids and less widely for chronic spontaneous urticaria.

Allergic asthma
Omalizumab is used to treat people with severe, persistent allergic asthma, uncontrollable with oral or injectable corticosteroids. Those patients have already failed step I to step IV treatments and are in step V of treatment. Such a treatment scheme is consistent with the widely adopted guidelines for the management and prevention of asthma, issued by Global Initiative of Asthma (GINA), which was a medical guidelines organization launched in 1993 in collaboration with the National Heart, Lung, and Blood Institute, National Institutes of Health, USA, and the World Health Organization.

Chronic spontaneous urticaria
Omalizumab is indicated for chronic spontaneous urticaria in adults and adolescents (>12 years old) poorly responsive to H1-antihistamine therapy. When administered subcutaneously once every four weeks, omalizumab has been shown to significantly decrease itch severity and hive count.