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Xolair Side Effects

Generic Name: omalizumab

Note: This page contains side effects data for the generic drug omalizumab. It is possible that some of the dosage forms included below may not apply to the brand name Xolair.

In Summary

More frequent side effects include: lower 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 (the active ingredient contained in Xolair) 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

Minor Side Effects

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


The more commonly reported side effects included injection site reactions, headache, and nasopharyngitis.[Ref]


In clinical trials, any injection site reaction occurred in 45% and 43% of patients given this drug and placebo, respectively; severe reactions occurred in 12% and 9%, respectively.[Ref]

Very common (10% or more): Any injection site reaction, including pain, swelling, itching, redness, bruising, bleeding, induration, or mass (up to 45%), severe injection site reaction (up to 12%)
Uncommon (0.1% to 1%): Arm swelling[Ref]


Very common (10% or more): Viral infection (up to 37%)
Uncommon (0.1% to 1%): Moniliasis, parasitic infection
Rare (0.01% to 0.1%): Anti-omalizumab (the active ingredient contained in Xolair) antibody development
Postmarketing reports: Serum sickness, allergic granulomatous angiitis (Churg-Strauss syndrome), lymphadenopathy[Ref]

In clinical studies, viral infection occurred in 37% and 39% or patients given this drug or placebo, respectively. Increased parasitic infections, compared to placebo, were not statistically significant.[Ref]

Nervous system

Very common (10% or more): Headache (up to 27%)
Common (1% to 10%): Dizziness
Uncommon (0.1% to 1%): Syncope, vasovagal syncope, somnolence, paresthesia
Frequency not reported: Migraine, sinus headache[Ref]

In clinical trials, headache occurred in 37% of patients given either this drug (n=716) or placebo (n=694); headache occurred very commonly in patients 6 to 12 years old.[Ref]


Very common (10% or more): Back pain (up to 13%)
Common (1% to 10%): Arthralgia, myalgia, sprains, strains, extremity pain, fracture
Postmarketing reports: Joint swelling[Ref]


In clinical trials with chronic idiopathic urticarial, patients reported nasopharyngitis 9.1%, 6.6%, and 7% in 150 mg, 300 mg, and placebo, respectively; sinusitis (1.1%, 4.9%, 2.1%), cough (1.1%, 2.2%,1.2%), and upper respiratory infection (11.1%, 3.4%, 2.1%) were also reported by patients, respectively.[Ref]

Common (1% to 10%): Nasopharyngitis, sinusitis, viral upper respiratory infection (URI), URI
Uncommon (0.1% to 1%): Pharyngitis, cough, allergic bronchospasm
Rare (0.01% to 0.1%): Laryngoedema
Frequency not reported: Asthma, oropharyngeal pain[Ref]


Common (1% to 10%): Dermatitis, pruritus
Uncommon (0.1% to 1%): Skin rashes, flushing, photosensitivity
Postmarketing reports: Alopecia, hair loss[Ref]


Common (1% to 10%): Fever, earache
Uncommon (0.1% to 1%): Fatigue, post-injection phenomena[Ref]

In clinical trials, fever occurred very commonly in patients 6 to 12 years old.[Ref]


In clinical trials, upper abdominal pain was very common in patients 6 to 12 years old. In clinical trials with chronic idiopathic urticarial, patients reported nausea 1.1%, 2.7%, and 2.5% of the time with 150 mg, 300 mg, and placebo, respectively.[Ref]

Common (1% to 10%): Upper abdominal pain, nausea
Uncommon (0.1% to 1%): Diarrhea, dyspepsia, gastroenteritis
Frequency not reported: Toothache[Ref]


Common (1% to 10%): Urinary tract infection[Ref]


Uncommon (0.1% to 1%): Urticaria
Rare (0.01% to 0.1%): Anaphylactic reactions, angioedema
Postmarketing reports: Anaphylactoid reactions[Ref]


Uncommon (0.1% to 1%): Postural hypotension
Frequency not reported: Peripheral edema, arterial thrombotic events (including transient ischemic attack, myocardial infarction, unstable angina, and cardiovascular death)
Postmarketing reports: Hypotension, chest tightness[Ref]


Uncommon (0.1% to 1%): Asymptomatic platelet decreases
Postmarketing reports: Idiopathic severe thrombocytopenia, eosinophilic conditions[Ref]

In clinical trials, 0.6% of patients developed decreased platelet counts below the normal laboratory range; these patients did not have associated bleeding episodes or decreased hemoglobin.[Ref]


Uncommon (0.1% to 1%): Weight increases[Ref]


Frequency not reported: Anxiety[Ref]


1. Cerner Multum, Inc. "Australian Product Information." O 0

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

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

It is possible that some side effects of Xolair 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.