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What Is Hereditary Angioedema (HAE)?

What Is Hereditary Angioedema?

Angioedema is swelling (edema) under the skin. It can happen in different parts of your body, and it’s usually caused by an allergic reaction.

When you have hereditary angioedema (HAE), a rare genetic condition causes the swelling, not allergies. You are born with this condition and will always have it.

Treatment can help you live with it, though. Over the years, there have been big improvements in therapies, and researchers are still looking for more and better treatment options.

Symptoms usually 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.

With this disease, the 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. Where you have it, how often the bouts happen, and how strong they are, is different for everyone. The attacks can come and go, as well as move to different spots during the same bout.

Your throat can swell. That can cut off your airway, which is life threatening. So, if you know you have HAE, and you feel any change like that, get help right away.

Without treatment, you can have attacks as often as every 1 to 2 weeks, and they can be hard to manage.


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

If one of your parents has HAE, you have a 50% chance of having it, too. But sometimes the gene change happens for unknown reasons while a child is in the womb. 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 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
  • Private parts
  • Belly

Swelling in the throat is the most dangerous symptom. It can cut off your air supply.

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 early warning signs before swelling begins. These may include:

  • Extreme fatigue
  • Rash on arms or legs
  • Muscle aches
  • Tingling
  • Headache
  • Belly pain
  • Hoarseness
  • Mood changes

HAE Triggers

You may not be able to tell what your triggers are, but here are some common ones:

  • 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:

  • Having your period
  • Being pregnant: For some women, it doesn't happen as often when they’re carrying a baby, but then the attacks come back after they give birth.
  • Using birth control or hormone replacement therapy: Women usually say they have more and worse attacks while on these drugs.

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