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Xolair Side Effects

Generic Name: omalizumab

Note: This document contains side effect information about omalizumab. Some of the dosage forms listed on this page 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

Along with its needed effects, omalizumab (the active ingredient contained in Xolair) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking omalizumab:


Some side effects of omalizumab may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions 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.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.