Hereditary and Acquired C1 Inhibitor Deficiency

(Hereditary and Acquired Angioedema)

Reviewed/Revised Oct 2024
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What are hereditary and acquired C1 inhibitor deficiency?

Hereditary and acquired C1 inhibitor deficiency are also known as hereditary and acquired angioedema. Angioedema is swelling of your face, lips, tongue, and throat that is usually caused by an allergic reaction. But angioedema can also be caused by a certain problem with your immune system.

  • Hereditary angioedema (also called hereditary C1 inhibitor deficiency) is an immune system problem you're born with

  • Acquired angioedema (also called acquired C1 inhibitor deficiency) is an immune system problem caused by another illness or condition

Hereditary and acquired angioedema are like angioedema caused by an allergic reaction, but they don't itch and you don't get hives (red, itchy, raised patches on the skin).

  • Your lips, tongue, and throat may swell, which can cause trouble breathing

  • You may feel sick to your stomach and throw up

  • Doctors can use medicines to treat and prevent the swelling

What causes hereditary or acquired angioedema?

Hereditary angioedema is genetic (a trait inherited from a parent). The condition is present at birth, but symptoms usually start when you’re a child or teenager.

Acquired angioedema can develop after you get certain cancers or autoimmune diseases (a disease that causes your body's immune system to attack its own tissues). Symptoms usually start later in life.

What can trigger an attack of angioedema?

In both hereditary and acquired angioedema, swelling may be triggered by:

  • Minor injury

  • Infection

  • Certain foods

  • Pregnancy

  • Cold

  • Stress

What are the symptoms of hereditary and acquired angioedema?

Symptoms can include painful swelling in your:

  • Face

  • Lips

  • Tongue

  • Hands

  • Feet

  • Genitals

  • Lining of your mouth, throat, airways, and digestive tract

Other symptoms include:

  • Feeling sick to your stomach

  • Throwing up

  • Cramps

Swelling in the voice box, throat, or tongue can cause breathing problems.

Images of Angioedema
Angioedema
Angioedema

This photo shows swelling of the lips in a person with hereditary angioedema.

By permission of the publisher. From Joe E, Soter N. In Current Dermatologic Diagnosis and Treatment, edited by I Freedberg, IM Freedberg, and MR Sanchez. Philadelphia, Current Medicine, 2001.

Angioedema of the Tongue
Angioedema of the Tongue

This person has a swollen tongue due to angioedema.

SCIENCE PHOTO LIBRARY

Angioedema of the Lips
Angioedema of the Lips

This person has swollen lips due to angioedema.

DR P. MARAZZI/SCIENCE PHOTO LIBRARY

How can doctors tell if I have hereditary or acquired angioedema?

Doctors suspect hereditary or acquired angioedema if you have swelling but no hives. To know for sure, they'll do:

  • Blood tests

How do doctors treat hereditary and acquired angioedema?

Doctors treat you with:

  • Medicine that helps your immune system

Doctors may also give you medicines to prevent swelling, particularly before known triggers.

Blocked airway treatment

If your airway swells and you have problems breathing, doctors will need to open your airway. To do this, they may:

  • Give you a shot to lessen swelling

  • Put in a breathing tube through your nose or mouth

  • If there is too much swelling around the nose and mouth, put in a breathing tube by cutting into the skin over your windpipe

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