Xolair Side Effects

As of June 30, 2024, asthma, shortness of breath and hives were the most common Xolair side effects reported to the U.S. Food and Drug Administration through their Adverse Events Reporting System. FAERS data represent reactions reported between 2002 and 2024.

These three conditions accounted for over a third of all side effects reported.

Overall, practitioners and consumers reported 2,706 cases of anaphylaxis as a Xolair reaction. Reported cases of Xolair side effects were highest in 2017, with 7,210 reports, followed by 2023, which had 4,890 reports.

Disclaimer: Reports sent to the FDA don’t necessarily mean the drug caused an adverse event. Consult a health care professional before stopping or changing medication.

FAERS data represent all reported cases of reactions for people taking a drug. While it does not necessarily prove a causal relationship between the drug and the reaction, patients should still be aware of the potential side effects.

Clinical trial data reported on the drug packaging shows that the most frequent Xolair side effects include reaction at the injection site, increased infections, sinusitis, headache and sore throat. Generally, the rates of these adverse reactions were similar among people taking Xolair and those who received a placebo. However, severe reactions at the injection site were 3% more common in patients who received Xolair.

The drug packaging also indicates that pediatric patients have a higher incidence of side effects when taking Xolair compared to control groups. Reactions reported include common cold, headache, fever, upper abdominal pain, strep throat, ear infections, stomach viruses and nose bleeds.

Xolair side effects occur in a small percentage of people, especially compared to placebo groups in clinical trials. Many medical professionals consider the drug a safe treatment option for specific types of allergy-induced asthma, chronic hives and food allergies, and it has FDA approval for those uses.

Xolair may cause serious side effects such as elevated eosinophils (a type of white blood cell related to immune function) and problems with blood vessels. It’s also associated with an increased risk of certain types of cancer, although recent data may contest its link to cancer.

In February 2024, the FDA approved Xolair for treating those who had a reaction to severe food allergies. This was after a clinical trial showed primarily mild adverse reactions.

The most recently released study data reports four serious adverse effects in trial participants on omalizumab, Xolair’s active ingredient. Two of these effects were psychiatric, one involved infection and the last patient showed reduced liver function tests.

Severe side effects from Xolair are rare. However, they can be dangerous and are sometimes fatal. If you suspect a serious reaction or show symptoms of one, report it to your health care provider immediately.

Blood Vessel Inflammation

There is an increased risk of systemic eosinophilia when taking Xolair. This is when there is a buildup of excess white blood cells, called eosinophils, which causes blood vessel inflammation. Left untreated, it can lead to an aneurysm. A large aneurysm may burst, which can be fatal.

Xolair packaging contains a warning about the possibility of eosinophilia and blood vessel disorders. According to the manufacturer’s safety information, you should immediately report symptoms such as chest pain, rash, shortness of breath, pins and needles and numbness of the arms or legs to your doctor.

Cancer Risk

The most recent data does not indicate increased cancer risk, although patients in the initial clinical trials had slightly higher rates of cancer. These included breast cancer, melanoma, non-melanoma skin cancer and prostate cancer. Prescribing information shows that 0.5% of clinical trial participants receiving Xolair developed some form of cancer compared to 0.2% of control subjects.

In a later observational study, however, researchers observed patients on the drug and those not taking it for up to five years, and they found that malignancy outcomes were similar in both groups.

The FDA noted that several study limitations prevented a definitive finding, meaning they could not confirm nor completely discount a malignancy risk. Additionally, people with asthma tend to have higher rates of lung cancer, regardless of treatment.

Recent research does not show a statistically significant increase in malignancy between study participants taking Xolair and those in control groups. A 2024 retrospective study in Asia Pacific Allergy, for example, found no increased risk of tumors in patients taking monoclonal antibodies such as Xolair.

In July 2007, the FDA issued guidance requiring Xolair manufacturer Genetech to include a black box warning about the risk of anaphylaxis when taking Xolair. A boxed warning is the most serious type the FDA can require and indicates that the drug may cause serious injury or death. Anaphylaxis is a known risk that can be fatal.

Symptoms of anaphylaxis include a red rash, swelling of the mouth or throat, shortness of breath, tightening in your chest and lightheadedness. Failure to receive immediate medical care could be fatal.

Editor Lindsay Donaldson contributed to this article.