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Anti-C1-INH antibodies
May also test positive for ANA, anti-thyroid, or other autoimmune markers
Autoimmune angioedema is a rare condition where the immune system mistakenly triggers swelling in the deeper layers of the skin or mucous membranes—like the face, lips, tongue, throat, hands, or digestive tract. This swelling can be unpredictable and scary, especially if it affects breathing or causes stomach pain.
In autoimmune angioedema, the immune system may interfere with a protein called C1 inhibitor, leading to abnormal activation of the body’s inflammatory pathways.
Sudden swelling in the face, lips, eyelids, hands, feet, or genitals
Swelling of the tongue or throat, which can be dangerous
Abdominal pain, cramping, nausea, or vomiting (if swelling occurs in the gut)
No hives or rash, unlike typical allergic reactions
Episodes can last for hours to days, and may come and go over time
Autoimmune angioedema is not caused by allergies. Instead, it’s triggered by:
The body making autoantibodies (proteins that attack your own tissues)
These autoantibodies interfere with C1 inhibitor, a protein that controls inflammation
It may be linked to other autoimmune diseases like:
Lupus (SLE)
Rheumatoid arthritis
Hashimoto’s thyroiditis
Some people may also develop angioedema after infections or in connection with certain types of lymphomas.
Doctors may run the following tests:
C1 inhibitor (C1-INH) levels and function
C4 complement levels (often low during attacks)
ANA or other autoimmune antibody tests
Detailed history of episodes to rule out allergies or medications like ACE inhibitors
Treatment focuses on preventing or reducing swelling episodes:
C1 inhibitor replacement therapy (for those with low levels)
Immunosuppressants or corticosteroids to calm the immune system
Antihistamines or epinephrine (less effective unless histamine is involved)
Fresh frozen plasma in emergency settings (contains C1-INH)
Avoid known triggers like stress, certain medications, or trauma (if identified)
Emergency treatment may include airway management if breathing is affected
Many people manage it well with treatment and lifestyle adjustments
Swelling can be unpredictable, and severe episodes (especially in the throat) are medical emergencies
Ongoing care and monitoring for other autoimmune conditions is often needed
Very rare – estimated fewer than 1 in 50,000 people
May be underdiagnosed, especially when symptoms are mistaken for allergies
Affects both men and women, often diagnosed in adulthood
Zuraw, B. L. (2008). Hereditary angioedema. New England Journal of Medicine, 359(10), 1027–1036.
https://doi.org/10.1056/NEJMra0803977
→ Describes the mechanisms of angioedema, including autoimmune forms.
Gompels, M. M., Lock, R. J., & Abinun, M. (2005). C1 inhibitor deficiency: Consensus document. Clinical and Experimental Immunology, 139(3), 379–394.
https://doi.org/10.1111/j.1365-2249.2005.02897.x
→ Outlines diagnostic criteria and autoimmune associations.
NORD – National Organization for Rare Disorders. (2022). Acquired Angioedema.
https://rarediseases.org/rare-diseases/acquired-angioedema/
→ Patient-friendly overview of acquired and autoimmune angioedema.
Cicardi, M., & Zanichelli, A. (2010). Acquired angioedema. Allergy, Asthma & Clinical Immunology, 6(1), 14.
https://doi.org/10.1186/1710-1492-6-14
→ Discusses autoimmune causes and treatment options.
U.S. National Library of Medicine – MedlinePlus. (2023). Angioedema.
https://medlineplus.gov/angioedema.html
→ General overview of angioedema types and symptoms.
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