Angioedema is the formal medical term for swelling under the skin. It usually occurs as part of an allergic reaction, but has forms that are not due to allergies.
Angioedema is related to hives, which are referred to as urticaria in formal medical language. But hives are swelling in the upper layers of the skin, the epidermis and dermis, whereas angioedema is swelling in deeper layers, the subcutaneous and submucosal layers.
Angioedema and hives often occur at the same time. However, angioedema causes large, thick welts which may not be itchy, whereas hives are smaller and usually itchy. Angioedema most frequently occurs around the eye and lip areas of the face. Affected areas are often painful, warm, and red.
Serious cases of angioedema in the throat or tongue can be life-threatening, because swelling can make breathing difficult.
Most cases of angioedema are acute, meaning they only last for a few days. Acute angioedema almost always occurs with hives, and both are part of an allergic reaction. In some cases, angioedema occurs without hives and is not an allergic reaction.
Causes and types
Acute angioedema often occurs as part of an allergic reaction to various allergens or triggers. These can include certain foods, insect bites or stings, medications, and natural rubber products like latex.
When doctors cannot figure out the cause a health issue, the condition is called idiopathic. Most cases of angioedema are idiopathic, but research also suggests that many idiopathic angioedema cases are related to autoimmune disorders such as lupus.
Hereditary angioedema is a rare inherited disease that affects the production and/or function of one of two blood proteins: C1 inhibitor protein (involved in the immune system) or coagulation factor XII (involved in blood clotting). This disease is inherited in an autosomal dominant pattern, meaning that one copy of the defective gene — inherited from either parent — is sufficient for a person to develop the disease.
In some cases, a deficiency in the C1 inhibitor protein is acquired later in life, rather than inherited at birth. Such cases are called acquired C1 inhibitor deficiency angioedema and may be due to the immune system attacking the C1 inhibitor protein.
Angioedema is diagnosed following the examination of the affected area and a careful medical history.
If allergic angioedema is suspected, doctors may perform an allergy test.
If hereditary angioedema is suspected, a blood test may be performed to check for the presence of abnormal blood proteins (C1 inhibitor protein or coagulation factor XII).
Treatment depends on the severity and cause of the condition. Many cases of angioedema are short-lived and will clear up on their own without medication.
Angioedema due to a non-allergic drug reaction can be resolved by switching to a medication that does not trigger angioedema.
Angioedema related to an allergy will typically be treated with antihistamine medications that dampen the allergic response. More severe cases may be treated with anti-inflammatory drugs, such as oral corticosteroids. If these treatments are not effective, doctors may prescribe an immunosuppressant medication to lessen the immune response that is causing the angioedema.
Long-lasting or chronic angioedema can be treated with a type of anti-inflammatory medication called a leukotriene antagonist, such as montelukast. This type of medication may be preferred for long-term use.
Patients with a history of severe angioedema in the throat or tongue may be prescribed an EpiPen (self-injected, intra-muscular injection of epinephrine) to be used in case of emergency.
Hereditary angioedema does not respond to antihistamines or corticosteroids, and is typically treated with medications designed to regulate blood proteins. Acute attacks of hereditary angioedema are treated with intravenous C1 inhibitor concentrates.
Acquired C1 inhibitor deficiency angioedema is treated in a similar manner to hereditary angioedema.
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