What the label lists and what reports show
Omalizumab side effects
Omalizumab's FDA label: “The most common adverse reactions (≥ 1% of patients) in clinical studies with adult and adolescent patients ≥12 years of age were arthralgia, pain (general), leg pain, fatigue, dizziness, fracture, arm pain, pruritus, dermatitis, and earache.” FAERS holds 84,758 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is dyspnoea (10,337 reports).
- No generic listed
- Boxed warning
Check it at the source: the omalizumab FDA label on DailyMed (effective August 13, 2026, Genentech, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of XOLAIR?XOLAIR may cause serious side effects, including: See " What is the most important information I should know about XOLAIR? " Cancer. Cases of cancer were observed in some people who received XOLAIR. Inflammation of your blood vessels. Rarely, this can happen in people with asthma who receive XOLAIR. This usually, but not always, happens in people who also take a steroid medicine by mouth that is being stopped or the dose is being lowered. It is not known whether this is caused by XOLAIR. Tell your healthcare provider right away if you have: rash shortness of breath chest pain a feeling of pins and needles or numbness of your arms or legs Fever, muscle aches, and rash. Some people get these symptoms 1 to 5 days after receiving a XOLAIR injection. If you have any of these symptoms, tell your healthcare provider. Parasitic infection. […]
Source: FDA drug label, Genentech, Inc., effective August 13, 2026 (SPL set 7f6a2191-adfb-48b9-9bfa-0d9920479f0d), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsThe most common adverse reactions (≥ 1% of patients) in clinical studies with adult and adolescent patients ≥12 years of age were arthralgia, pain (general), leg pain, fatigue, dizziness, fracture, arm pain, pruritus, dermatitis, and earache.
Table 7. Adverse Reactions ≥1% More Frequent in XOLAIR-Treated Adult or Adolescent Patients 12 years of Age and Older in Four Placebo-controlled Asthma Trials
| Adverse reaction | XOLAIR n=738 | Placebo n=717 |
|---|---|---|
| Pain | 7% | 5% |
| Fatigue | 3% | 2% |
| Arthralgia | 8% | 6% |
| Fracture | 2% | 1% |
| Leg pain | 4% | 2% |
| Arm pain | 2% | 1% |
| Dizziness | 3% | 2% |
| Pruritus | 2% | 1% |
| Dermatitis | 2% | 1% |
| Earache | 2% | 1% |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse reactions are described elsewhere in the labeling: Anaphylaxis [see Boxed Warning and Warnings and Precautions (5.1) ] Malignancies [see Warnings and Precautions (5.2) ] Asthma: The most common adverse reactions (≥ 1% of patients) in clinical studies with adult and adolescent patients ≥12 years of age were arthralgia, pain (general), leg pain, fatigue, dizziness, fracture, arm pain, pruritus, dermatitis, and earache. In clinical studies with pediatric patients 6 to <12 years of age, the most common adverse reactions (≥3% of patients) were nasopharyngitis, headache, pyrexia, upper abdominal pain, pharyngitis streptococcal, otitis media, viral gastroenteritis, arthropod bites, and epistaxis. ( 6.1 ) Chronic Rhinosinusitis with Nasal Polyps: The most common adverse reactions (≥ 3% of patients) in clinical studies with adult patients included the following: headache, injection site reaction, arthralgia, upper abdominal pain, and dizziness. ( 6.1 ) IgE-Mediated Food Allergy: The most common adverse reactions (≥3% of patients) were injection site reactions and pyrexia. ( 6.1 ) Chronic Spontaneous Urticaria: The most common adverse reactions (≥2% of patients) included the following: nausea, nasopharyngitis, sinusitis, upper respiratory tract infection, viral upper respiratory tract infection, arthralgia, headache, and cough.
Source: FDA drug label, Genentech, Inc., effective August 13, 2026 (SPL set 7f6a2191-adfb-48b9-9bfa-0d9920479f0d), via openFDA; the full label on DailyMed
What do FAERS reports show?
84,758 reports list omalizumab among the medicines taken, each a report of something that happened, not proof the medicine caused it; 2,453 are coded as a death and 15,677 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 20 reactions below, 12 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Omalizumab: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions