Idiopathic Anaphylaxis

About the study

Idiopathic anaphylaxis (IA) is a condition in which anaphylaxis occurs without any known external trigger. The most common causes of anaphylaxis are reactions to foods, drugs, and stinging insects, but a cause is not identified in up to 50 percent of people with recurrent anaphylaxis. Volunteer participants in this study will help National Institutes of Health (NIH) researchers try to identify the cause and development of IA. Findings from this study may be a first step toward the development of new medicines and treatments.

What does the study involve?

If you have been diagnosed with idiopathic anaphylaxis and are interested in participating in this clinical research study, you will be asked to answer some questions and then make one or two visits to NIH in Bethesda, Maryland, to determine your eligibility. During these visits, study staff will take a sample of your blood. They also may take a sample of bone marrow from your hip. Your participation in the study will continue for up to 12 months, the first 6 months of which you will receive the study drug every 2 or 4 weeks in a randomized placebo-controlled trial (you may or may not receive the active drug, and this is determined similar to a coin toss). You may receive a thorough medical evaluation to exclude known causes of anaphylaxis, if necessary. You or your insurance carrier will not be charged for study-related procedures or medications.

Where is the study taking place?

The study is being conducted at the NIH Clinical Center in Bethesda, Maryland, which is accessible by car and public transportation. After you are accepted in the study, you may be reimbursed for your travel expenses.

Who can participate?

You may be able to participate in the study if all of the following apply to you:

  • You are between 18 and 70 years of age.
  • You have been diagnosed with idiopathic anaphylaxis.
  • You have a documented history of anaphylaxis that occurs at least six times per year and have experienced one of the following within the past four months:
    • Emergency room visit or hospitalization due to documented anaphylaxis
    • High level of serum tryptase within two hours of an anaphylactic event
  • You can get a referral letter and medical history record from your doctor.
  • You agree to use effective contraception or practice abstinence.

You cannot participate in the study if any of the following apply to you:

  • You have a known cause for your anaphylaxis.
  • You use beta blockers.
  • You cannot have or refuse to have a sample of bone marrow taken from your hip.
  • You are HIV-positive.
  • You have active or chronic hepatitis.
  • You currently have or have a history of a malignancy.
  • You are currently taking, or have taken within 30 days of the study, any other investigational medication.
  • You are pregnant or nursing.
  • You cannot travel to NIH in Bethesda, Maryland.

To learn more about this study, visit

Content last reviewed on February 13, 2015