Hereditary Angioedema (HAE)

Medically Reviewed by Stephanie S. Gardner, MD on September 18, 2023
5 min read

Hereditary angioedema is a rare genetic condition that causes swelling under the skin and lining of the gut and lungs. It can happen in different parts of your body.

You are born with hereditary angioedema (HAE). Although you’ll always have it, treatment helps you manage it.

There have been big improvements in treatment, and researchers continue to look for new solutions.

Symptoms most often initially show up in childhood and get worse during the teen years. Many people don't know HAE is causing their swelling until they're adults. Where you have it on your body, how often the bouts happen, and how strong they are different for everyone. The attacks can come and go as well as move to different spots during the same bout. The swelling typically goes away on its own but can also occur as a life-threatening event.

Your throat can swell. That can cut off your airways and could be deadly. So if you know you have HAE and you feel any change like that, call 911 right away.

The frequency of attacks can vary. You can have attacks as often as every 1 to 2 weeks or 1 to 2 per year, and they can be hard to manage.

With this disease, a certain protein in your body is not in balance. This causes tiny blood vessels to push fluid into nearby areas of your body. That leads to sudden swelling.

A problem with a gene that makes a blood protein called C1 inhibitor often causes HAE. In most cases, you don’t have enough of this protein. In others, you have normal levels but it doesn't work right.

For the most common form of HAE, if one of your parents has HAE, you have a 50% change of having it, too. But sometimes the gene change happens for unknown reasons. If you have the broken gene, you can pass it on to your children.

The main symptom is swelling. You won’t have the itching or hives that people often get with allergic reactions. A bout may last 2 to 5 days.

It can happen in different parts of the body:

  • Mouth or throat
  • Hands
  • Feet
  • Face
  • Genitals
  • Belly

Swelling in the throat is the most dangerous symptom.

Puffiness in the feet and hands can be painful and make it hard to go about your daily life.

Swelling in your belly can cause:

  • Extreme pain
  • Nausea
  • Vomiting
  • Diarrhea

You may notice warning signs before swelling begins. These may include:

  • Extreme fatigue
  • Muscle ache
  • Tingling
  • Headache
  • Belly pain
  • Hoarseness
  • Mood changes

Although you may not be able to tell what your triggers are, common ones include:

  • Stress or anxiety
  • Minor injury or surgery
  • Illnesses such as colds or flu
  • Physical activities such as typing, hammering, or pushing a lawn mower
  • Medications, including some used for high blood pressure and congestive heart failure

Women may notice a difference in the number or sharpness of attacks when they:

  • Have their period
  • Are pregnant. For some women, it doesn't happen as often when they’re pregnant, but then the attacks come back after they give birth.
  • Use birth control or hormone replacement therapy containing estrogen. Women usually say they have more and worse attacks while on these medicines.

If you've had symptoms of HAE, your doctor may ask:

  • What changes have you noticed?
  • Where have you had swelling? How often?
  • Have you had any in your face, neck, tongue, or throat?
  • Have you noticed any changes that happen before swelling begins?
  • Have you had any stomach problems or stomach surgery?
  • Does anyone in your family have a problem with swelling?
  • Have you or anyone in your family been treated for allergies?

The right diagnosis is key. Sometimes people are treated for allergies when it's really HAE that causes their swelling. Antihistamines and corticosteroids that treat allergies don’t work well for this disease.

You can have severe stomach swelling, pain, and diarrhea and severe dehydration and if misdiagnosed, it can lead to surgery you don't need.

Your doctor will do a physical exam. You'll need blood tests, too, to confirm that it’s HAE.

If you do have it, ask your doctor to refer you to a specialist familiar with the condition. You should also ask your doctor about having other members of your family tested, even if no one has symptoms.

  • Do I need more tests?
  • What can I expect from this condition?
  • Which treatments do you recommend? What are their side effects?
  • What should I do if my throat swells? How likely is that?
  • How can I find out what triggers my attacks?
  • Will I pass this condition on to my children?
  • Should my family get tested for HAE?
  • Will this affect my plans to have a family?

Doctors can use medications to treat or prevent attacks:

You may also need oxygen or IV fluids to ease your symptoms.

Your doctor will make recommendations for what you need.

Learn as much as you can about HAE so you can make informed decisions about your treatment and medications that you should be cautious with.

If you can figure out your triggers, you can better avoid them. It helps to track your attacks and symptoms in a journal and look for patterns.

Talk to your doctor before you have any dental work. They may want you to take medication to avoid a flare. Also talk with your doctor before you take any new prescription medicines. There is a chance they could trigger an attack.

Carry your medical information with you at all times.

If your child has HAE, note any changes in behavior that you see before an attack. As they get older, they'll need to learn their triggers and treatment needs.

Make sure all caregivers and family members know about the condition and what to do if an attack happens.

Remember: Any swelling in the throat is an emergency. Take your medication for attacks and call 911.

Connect with others who are living with HAE. They can share their insights and tips to help you manage your symptoms.

There's no cure for HAE, but new treatments have made it possible for people to manage their symptoms and enjoy active lives.

To learn more about HAE and to find the support of others who have it, visit the website of the U.S. Hereditary Angioedema Association at

Show Sources


HAEA: “What is HAE?” "Treating HAE."

American Academy of Allergy, Asthma and Immunology: “Understanding Hereditary Angioedema.”

Chnniah, N. Australia and New Zealand Journal of Obstetrics and Gynaecology, February 2009.

National Center for Advance Translational Sciences: “Hereditary angioedema.”

National Library of Medicine, Genetics Home Reference: "What is hereditary angioedema?"

National Organization for Rare Disorders: “Angioedema, Hereditary.”

HAECanada: “Frequently Asked Questions.”

U.S. Hereditary Angioedema Association: "FDA Approved Treatments."

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