Omalizumab, marketed under the brand name Xolair, is a monoclonal antibody used primarily to treat moderate to severe persistent asthma that's not adequately controlled with inhaled corticosteroids. It's also used for chronic idiopathic urticaria (chronic hives) that doesn't respond to antihistamines.

Omalizumab works by targeting and binding to immunoglobulin E (IgE), a substance in the body that plays a key role in allergic reactions. By reducing free IgE levels, the medication helps decrease the allergic response and inflammation in the airways, leading to fewer asthma attacks and less severe symptoms.

Administered via subcutaneous injection, typically every two to four weeks, the dosage of omalizumab depends on the patient's weight and IgE levels. As with any medication, there are potential side effects, including injection site reactions, headaches, and an increased risk of infections. In rare cases, it can cause severe allergic reactions, so it's important for patients to be monitored by healthcare professionals during treatment.

If you're considering omalizumab as a treatment option, it's essential to consult with your healthcare provider to determine if it's appropriate for your condition and to discuss any potential risks and benefits.