omalizumab
Brand names: Xolair
Xolair is a medicine that can help with asthma, nasal polyps, food allergies, and chronic hives. It works by blocking a substance in your body called IgE.
What it does
Xolair can treat moderate to severe asthma in people 6 years and older who have allergies.
Common side effects
Joint pain, General pain, Leg pain
Key warnings
Xolair can cause a severe allergic reaction called anaphylaxis, even after the first dose or after you have been taking it for a year or more.
How It Works
Xolair is a special type of medicine called an anti-IgE monoclonal antibody. It blocks immunoglobulin E (IgE) in your body. IgE is a substance that causes allergic reactions and inflammation.
How to Take It
Xolair is given as a shot under the skin (subcutaneous injection). The dose and how often you get it (every 2 or 4 weeks) depends on your IgE levels and weight. Your doctor will test your IgE levels before you start Xolair. Doses may need to be adjusted if your weight changes a lot.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. It is not known how Xolair will affect your unborn baby, but poorly controlled asthma during pregnancy can be risky. Talk to your doctor about the risks and benefits of taking Xolair during pregnancy.
Missed Dose
If you miss a dose of Xolair, call your doctor right away to reschedule your injection. Do not double your next dose.
Storage
Keep Xolair in the refrigerator between 36°F and 46°F (2°C to 8°C) in its original carton, away from direct sunlight. It can be taken out of the fridge for a total of 2 days, but do not leave it above 77°F (25°C). Do not freeze Xolair.
Side Effects (from patient reports)
Based on 83,679 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 79,748 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
79,748
Death-Related Reports
2,390
Hospitalization Reports
15,129
Top Indication
Asthma
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | ASTHMA | 11,601 |
| 2 | URTICARIA | 10,326 |
| 3 | NO ADVERSE EVENT | 10,204 |
| 4 | OFF LABEL USE | 9,929 |
| 5 | DYSPNOEA | 9,876 |
| 6 | DRUG INEFFECTIVE | 7,778 |
| 7 | COUGH | 6,767 |
| 8 | PRURITUS | 5,942 |
| 9 | FATIGUE | 5,824 |
| 10 | MALAISE | 5,429 |
| 11 | WHEEZING | 5,239 |
| 12 | HEADACHE | 5,206 |
| 13 | PNEUMONIA | 4,979 |
| 14 | PAIN | 4,103 |
| 15 | ANAPHYLACTIC REACTION | 3,984 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Xolair can cause a severe allergic reaction called anaphylaxis, even after the first dose or after you have been taking it for a year or more. This reaction can cause trouble breathing, low blood pressure, fainting, hives, and swelling of the throat or tongue. Because of this risk, your doctor should give you Xolair in a healthcare setting where they can treat anaphylaxis. Watch for signs of anaphylaxis after each Xolair injection and seek immediate medical care if symptoms occur.
Common Questions
Can Xolair cure my asthma?
Can I use Xolair for a sudden asthma attack?
How long does it take for Xolair to work?
Will Xolair get rid of my nasal polyps?
Do I still need to avoid foods I am allergic to while taking Xolair?
Can Xolair completely prevent allergic reactions to food?
Can I stop taking my other allergy medicines while on Xolair?
What should I do if I have an allergic reaction after getting a Xolair injection?
Will Xolair cause me to gain weight?
Can I give myself Xolair injections at home?
What are the common side effects of omalizumab?
What drug class is omalizumab?
Is omalizumab safe during pregnancy?
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What the FDA Data Shows for omalizumab
The FDA label for omalizumab (sold under brand names such as Xolair) classifies it as a prescription-only medication in the Anti-IgE Monoclonal Antibody class. Xolair can treat moderate to severe asthma in people 6 years and older who have allergies. Official labeling lists 24 commonly reported side effects, including Joint pain, General pain, Leg pain.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 83,679 voluntary reports. Interaction data is drawn directly from FDA-approved prescribing information. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 2, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages