Skip to Content

Omalizumab Side Effects

More frequently reported side effects include leg pain. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to omalizumab: subcutaneous powder for solution

As well as its needed effects, omalizumab may cause unwanted side effects that require medical attention.

If any of the following side effects occur while taking omalizumab, check with your doctor or nurse immediately:

  • Cough
  • difficulty with swallowing
  • dizziness
  • fast heartbeat
  • hives, itching, or skin rash
  • malignant tumor
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • tightness in the chest
  • unusual tiredness or weakness

Some omalizumab side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common
  • Bleeding
  • blistering
  • body aches or pain
  • burning
  • chills
  • cold or flu-like symptoms
  • coldness
  • congestion
  • discoloration of the skin
  • dryness or soreness of the throat
  • feeling of pressure
  • fever
  • headache
  • hoarseness
  • itching
  • leg pain
  • lumps
  • muscle or joint pain
  • numbness
  • pain
  • pain or tenderness around the eyes and cheekbones
  • redness
  • runny nose
  • scarring
  • sore throat
  • soreness
  • stinging
  • stuffy or runny nose
  • swelling
  • tender, swollen glands in the neck
  • tenderness
  • tingling
  • ulceration
  • voice changes
  • warmth
Less common
  • Arm pain
  • blistering, crusting, irritation, itching, or reddening of the skin
  • body produces substance that can bind to drug making it less effective or cause side effects
  • cracked, dry, or scaly skin
  • earache
  • itching skin

For Healthcare Professionals

Applies to omalizumab: subcutaneous powder for injection


Anaphylaxis usually occurred within two hours of receiving a omalizumab subcutaneous injection. However, recent reports include patients who had delayed anaphylaxis with onset two to 24 hours or even longer after receiving omalizumab treatment. Anaphylaxis may occur after any dose of omalizumab including the first dose. Health care professionals who administer omalizumab should be prepared to manage life-threatening anaphylaxis and should observe their omalizumab-treated patients for at least two hours after omalizumab is given. Patients under treatment with omalizumab should be fully informed about the signs and symptoms of anaphylaxis, their chance of developing delayed anaphylaxis following omalizumab treatment, and how to treat it when it occurs.[Ref]

Hypersensitivity reactions including anaphylaxis, presenting as bronchospasm, hypotension, syncope, urticaria, and/or angioedema of the throat or tongue, has been reported to occur after administration of omalizumab. Anaphylaxis has occurred as early as after the first dose of omalizumab, but also has occurred beyond 1 year after beginning regularly administered treatment. Because of the risk of anaphylaxis, patients should be closely observed for an appropriate period of time after omalizumab administration, and health care providers administering omalizumab should be prepared to manage anaphylaxis that can be life-threatening. Patients should also be informed of the signs and symptoms of anaphylaxis and instructed to seek immediate medical care should symptoms occur.[Ref]


Local side effects have included injection site reactions in 45% of patients, including bruising, redness, warmth, burning, stinging, itching, hive formation, pain, indurations, mass, and inflammation. Severe injection site reactions occurred in 12% of patients (vs 9% with placebo). Most reactions occurred within 1 hour after injection, lasted for 8 days or less, and decreased in frequency with subsequent doses.[Ref]


Cardiovascular side effects have been reported including a study showing a disproportionate increase in ischemic heart disease, arrhythmias, cardiomyopathy, cardiac failure, pulmonary hypertension, cerebrovascular disorders, and embolic, thrombotic, and thrombophlebitic events in patients treated with omalizumab compared to a control group of patients not given the drug.


Dermatologic side effects have included pruritus (2%) and dermatitis (2%).[Ref]


Respiratory side effects have included upper respiratory tract infection (20%), sinusitis (16%), and pharyngitis (11%).[Ref]

Nervous system

Nervous system side effects have included headache (15%) and dizziness (3%).[Ref]


Musculoskeletal side effects have included arthralgia (8%), fracture (2%), leg pain (4%), and arm pain (2%).[Ref]


Oncologic side effects have included malignancies in 0.5% of patients (n=4127) compared with 0.2% of control patients (n=2236). The types of malignancies in omalizumab-treated patients included breast, skin (nonmelanoma), prostate, melanoma, and parotid.[Ref]


Other side effects have included viral infections (23%), pain (7%), fatigue (3%), and earache (2%). Three cases of Churg-Strauss syndrome have also been reported.[Ref]


1. "Product Information. Xolair (omalizumab)." Genentech, South San Francisco, CA.

2. Winchester DE, Jacob A, Murphy T "Omalizumab for asthma." N Engl J Med 355 (2006): 1281-2

3. Giavina-Bianchi P, Giavina-Bianchi M, Agondi R, Kalil J "Omalizumab and Churg-Strauss syndrome." J Allergy Clin Immunol 122 (2008): 217

It is possible that some side effects of omalizumab may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.