No Longer Accepting Cases

The FDA has warned that Xolair, a popular anti-asthma drug, may increase the risk of life-threatening heart attacks, stroke, blood clots, and even cancer.


Xolair (omalizumab) is an injection drug that is designed to reduce sensitivity to inhaled or ingested allergens. It is primarily used to prevent asthma attacks in patients who do not respond to corticosteroids in asthma inhalers. It is also used to treat chronic hives. Xolair is manufactured by Genentech and has been sold in the United States since 2003.

What is the problem?

When Xolair was approved, the FDA required Genentech to conduct a safety study. Although the study found evidence of serious blood vessel problems in the heart and brain, the FDA could not definitely confirm these risks because the study was not designed or carried out very well.

The FDA has issued two safety warnings. The first warning was published in July 2009 after the FDA began investigating cardiovascular and cerebrovascular side effects from Xolair.

In September 2014, the FDA published another warning after finding higher rates of deadly side effects, including:

  • Mini-strokes
  • Transient ischemic attacks
  • Heart attacks
  • Sudden, unexpected chest pain
  • High blood pressure in arteries of the lungs (pulmonary hypertension)
  • Blood clots in the lungs (pulmonary embolism)
  • Blood clots in veins (venous thrombosis)
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Conclusions were based on data from a 5-year safety study, Evaluating the Clinical Effectiveness and Long-Term Safety in Patients with Moderate to Severe Asthma (EXCELS). The study involved 5,000 asthma patients on Xolair and 2,500 asthma patients who did not take Xolair. Cardiovascular side effects appeared early in the study.

Xolair and Cancer

No one knows if Xolair increases the risk of cancer. Clinical trial found higher rates of cancer in patients on Xolair (0.5%) compared to a placebo (0.2%). This preliminary data has raised concern because these studies lasted only a few years, but many cancers take longer to develop.

The FDA did not find higher rates of cancer after reviewing data from EXCELS. However, they cannot rule out the possibility. This risk information has been added to the label on Xolair.