Acquired Angioedema

Acquired angioedema is an immune system disorder characterized by swelling that can be anywhere on the body, although the lips and the skin around the eyes are the most frequently affected.

The tongue and the mucous membranes of the throat, mouth, and intestines also may swell. If the swellings in these areas become too severe, they can block the digestive system or the airway and become painful and life-threatening. Such cases require immediate medical attention and emergency treatment.


Acquired angioedema is a form of angioedema in which the swellings take the form of large, smooth welts. These welts are restricted to the lower layers of the skin and mucous membranes, are not itchy, and disappear on their own within two to three days. Severe swelling in the intestines or digestive system can cause nausea, vomiting, and intense pain in the abdomen.

When severe swellings occur in the mouth or throat, they can block the airways and make it difficult to breathe. This can quickly and unexpectedly turn into a life-threatening emergency; asphyxiation due to a blocked airway is the most common cause of death related to acquired angioedema.

Most types of angioedema occur in adulthood, but the swellings in acquired angioedema usually appear a little later, at middle age (40-50).

The prognosis of all types of angioedema is generally good with treatment. However, with acquired angioedema, an underlying immune system problem is usually present, causing the swellings and affecting the individual’s overall health.


Acquired angioedema occurs when levels of a protein called C1-inhibitor (C1-I) are too low. This protein blocks the activity of two other proteins; plasma kallikrein and coagulation factor 12. These two proteins are important for blood clotting, inflammation, and wound healing.

As a part of their normal function, these proteins also increase the production of bradykinin, which causes blood vessels in the deep layers of the skin to widen and let fluid flow into the tissues, causing swelling. When there isn’t enough C1-I protein available, bradykinin levels can get too high and cause an angioedema attack.

Levels of C1-I protein can be too low due to one of two reasons, and according to the cause, acquired angioedema is classed as type 1 or type 2.

In type 1, the normal function of the immune system is disrupted and it produces molecules that affect the production or cause the destruction of C1-I in the body. This disruption can be caused by a B-cell lymphocyte disorder, an autoimmune disease, or cancer. In this type, the swellings can occur several years before other symptoms, making the cause difficult to determine.

Type 2 is an autoimmune disease where the body has developed antibodies that specifically target its own C1-I proteins. These antibodies mark C1-I for destruction and removal from the bloodstream.


In a life-threatening situation, where swelling in the throat or mouth has blocked the airway and the individual is having trouble breathing, an EpiPen (epinephrine) can be used.

If the EpiPen is ineffective, immediate physical intervention may be necessary. Artificial respiration methods such as cardiopulmonary resuscitation (CPR) may be used to keep the patient alive until swelling subsides enough for them to breathe on their own, or until mechanical ventilation options become available.

Medicines that boost the levels of C1-I in the body are very effective for treating acquired angioedema. These include Haegarda, Cinryze, and Kalbitor (ecallantide). Another medicine, Firazyr (icatibant), can be used in much the same way as an EpiPen for immediate, self-treatment of an acquired angioedema attack.

Treating the underlying cause of the disorder (an immune system-affecting disease in type 1 or autoimmune activity in type 2) also can help improve the symptoms of acquired angioedema.


Angioedema News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.