Hereditary angioedema (HAE) is a rare autosomal dominant genetic swelling disorder that affects about one in 50,000 people worldwide. It is caused by a deficiency in the C1 esterase inhibitor (C1-INH) plasma protein - one of the serine protease inhibitors - that plays a key role in regulating inflammation.

HAE is characterized by recurrent, unpredictable, debilitating and potentially life-threatening attacks of mucosal or submucosal non-urticaric, non-pitting edema that can occur anywhere in the body and has been well documented to affect the larynx, abdomen, face, extremities and urogenital tract. Though the frequency and severity of attacks vary dramatically among patients, the clinical presentations of the disorder can include:

  • Swelling of the hands and feet, which may be so uncomfortable that patients cannot participate in normal daily activities

  • Gastrointestinal attacks that cause excruciating abdominal pain, nausea, vomiting, diarrhea and dehydration

  • Laryngeal attacks that can lead to death due to asphyxiation

The frequency and severity of attacks vary widely among patients, even within the same individual. Symptoms of HAE can occur at any age, but most attacks start in the pediatric age group. In fact, 40 percent of HAE attacks begin before the age of five and 75 percent before the age of 15. Symptoms often worsen around puberty - an especially difficult time to cope with this disease - and then persist throughout a person's life. Most HAE attacks, which on average occur ever seven to 14 days and last two to five days, occur spontaneously with no apparent cause; however, emotional upset, stress, minor physical trauma and infections are triggers that have been documented in studies of HAE patients. In women, menstruation and pregnancy seem to have a major effect on disease activity.

If left untreated, HAE can be dangerous and potentially fatal because patients can experience upper airway edema that may lead to asphyxiation. Patients with no previous history of upper airway involvement are still at risk for asphyxiation because there is no correlation between anatomical location of previous attacks and likely location of future attacks. In acute laryngeal attacks, time to asphyxiation varies from as quickly as 20 minutes to 14 hours.

Symptoms are non-specific, and a diagnosis is not always obvious. A majority of people with HAE are initially misdiagnosed, and many experience delays in diagnosis of up to two decades. Treatments are available, so a timely and accurate diagnosis is more important than ever. Clinicians should consider HAE in their differential diagnosis of unexplained, episodic skin, mucosal or submucosal angioedema or abdominal pain.

Can you identify a patient with HAE? Learn more about the disease and how to recognize the symptoms.

Learn About HAE

We encourage you to talk about HAE with your colleagues and patients. Find a local HAE-treating physician to refer a patient.

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The information contained within this website is intended for healthcare professionals only. Please confirm that you are a healthcare professional to proceed. If you are a patient or carer and would like to learn more about HAE, please visit HAEi.org, the website of the International Patient Organization for C1 Inhibitor Deficiencies, or HAEA.org, the website of the U.S. Hereditary Angioedema Association.

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You are entering a website which is intended for healthcare professionals licensed to practice in the United States. By proceeding you indicate that you understand the above statement and are not a patient or caregiver. If you are a patient or caregiver and would like to learn more about HAE, please visit HAEA.org, the website of the U.S. Hereditary Angioedema Association, or HAEi.org, the website of the International Patient Organization for C1 Inhibitor Deficiencies.

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