IMPORTANT WARNING:Omalizumab injection may cause serious or life-threatening allergic reactions. You may experience an allergic reaction immediately after receiving a dose of omalizumab injection or up to 4 days later. Also, an allergic reaction can occur after you receive the first dose of medication or at any time during your treatment with omalizumab. Tell your doctor if you are allergic to omalizumab injection, and if you have or have ever had food or seasonal allergies, a serious or life-threatening allergic reaction to any medication, or sudden breathing problems. You will receive your first dose of omalizumab in a doctor''s office or medical facility and additional doses until your doctor feels that you are safe to receive omalizumab at home. You will stay in the office for some time after you receive the medication so your doctor can watch you closely for any signs of an allergic reaction. Tell your doctor if you experience any of the following symptoms: wheezing or difficulty breathing, shortness of breath, cough, chest tightness, dizziness, fainting, fast or weak heartbeat, anxiety, feeling that something bad is about to happen, flushing, itching, hives, feeling warm, swelling of the throat or tongue,throat tightness, hoarse voice, or difficulty swallowing. Call your doctor immediately or get immediate emergency medical attention if you experience any of these symptoms after you leave your doctor''s office or medical facility. Your doctor will give you the manufacturer''s patient information sheet (Medication Guide) each time you receive an injection of omalizumab. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit the Food and Drug Administration (FDA) website (http://www.fda.gov/Drugs/DrugSafety/ucm085729.htm) or the manufacturer''s website to obtain the Medication Guide.Talk to your doctor about the risks of receiving omalizumab injection. Why is this medication prescribed?Omalizumab injection is used to decrease the number of asthma attacks (sudden episodes of wheezing, shortness of breath, and trouble breathing) in adults and children 6 years of age and older with allergic asthma (asthma caused by inhaling substances such as dander, pollen, and dust mites) whose symptoms are not controlled with inhaled steroids. It is also used to treat nasal polyps (swelling of the lining of the nose) in adults whose symptoms are not controlled with inhaled steroids. Omalizumab is also used to treat chronic hives without a known cause that cannot successfully be treated with antihistamine medications such as diphenhydramine (Benadryl), cetirizine (Zyrtec), hydroxyzine (Vistaril), and loratadine (Claritin) in adults and children 12 years of age and older. Omalizumab is not used to treat other forms of hives or allergic conditions. Omalizumab injection is in a class of medications called monoclonal antibodies. It works by blocking the action of a certain natural substance in the body that causes the symptoms of allergic asthma, nasal polyps, and hives. How should this medicine be used?Omalizumab injection comes as a prefilled syringe and as a powder to be mixed with water to be injected subcutaneously (under the skin). When omalizumab is used to treat allergic asthma or nasal polyps, it is usually injected once every 2 or 4 weeks. You may receive one or more injections, depending on your weight and medical condition. When omalizumab is used to treat chronic hives, it is usually given once every 4 weeks. Your doctor will determine the length of your treatment based on your condition and how well you respond to the medication.