What Is Angioedema?

Swelling of the Skin Caused by an Allergic Reaction

Allergic angioedema. Note that this child is unable to open his eyes due to swelling.
Wikimedia Commons

Angioedema is a term used to describe the swelling of an area of skin, most commonly the face, tongue, throat, arms, or legs. It is caused when the immune system responds abnormally and releases a chemical called histamine into the bloodstream. This is the same chemical that can trigger hay fever (allergic rhinitis) and hives (urticaria).

However, unlike either of those conditions, angioedema occurs in the subcutaneous tissue just beneath the top layer of skin or mucous membrane.

It is neither itchy nor red but can often cause a tingling, numb, or burning sensation.

Angioedema may last several hours or days. When the swelling finally stops, the skin will usually appear normal with no flaking, peeling, scarring, or bruising.

Causes of Angioedema

Angioedema is typically the result of an allergic reaction to medications, foods, insect stings, or other substances such as latex. It may sometimes be accompanied by urticaria as both conditions are triggered by the same immune response.

Generally speaking, an allergic angioedema will develop within 20 to 30 minutes of eating food, taking a drug (such as an antibiotic), or getting stung by an insect. The swelling will not be like that of a rash with a defined border; rather, it will be more generalized in appearance.

In some cases, the angioedema may be idiopathic (of unknown origin) and triggered by anything from stress or strenuous exercise to minor infections or extreme changes in temperatures.

There is even a form of hereditary angioedema which is passed from parents to offspring.

Angioedema vs. Pseudo-Angioedema

There are times when the swelling of the lips, eyes, face, or hands may fit the classic description of angioedema but could end up something entirely different. We refer to this as pseudo-angioedema as it mimics the characteristics of a true angioedema.

Examples include:

  • Contact dermatitis, an allergic reaction in which the swelling is red and itchy and typically accompanied by eczema
  • Dermatomyositis, an autoimmune disorder of the skin and skeleton in which the swelling can persist for months and be accompanied by weight loss, fatigue, and fever
  • Hypothyroidism, in which the severe and prolonged drop in thyroid hormone can cause the thickening and crusting of the lower legs, face, and hands (myxedema)
  • Emphysema, in which chest injury caused by the lung disease can trap air bubbles beneath the skin
  • Superior vena cava syndrome, a condition in the which the obstruction of blood flow to the heart can cause swelling of the face and upper body
  • Granulomatosis, another autoimmune disorder characterized by the swelling of blood vessels, most often of the lips and face


The treatment of angioedema involves the tempering the immune response to reduce the levels of histamine circulating in the blood and to relieve inflammation in the subcutaneous layer of skin.

Among the possible options:

  • Oral antihistamines are typically prescribed to treat the allergy symptoms. Zyrtec (cetirizine) is particularly effective. Persons prone to angioedema often find sustainable relief with a low dose of Zyrtec taken nightly.
  • Recurrent or chronic angioedema (lasting for more than six months) may require a consultation with an allergist to identify the allergy triggers (allergens). By doing so, the doctor may be able to prescribe allergy shots to desensitize you to those allergens.
  • Chronic cases may respond well to systemic corticosteroids delivered by intramuscular injection. Prednisone is one of the more commonly prescribed options.
  • Severe angioedema may be a sign of a potentially life-threatening, all-body allergy called anaphylaxis. Persons at risk typically carry injectable epinephrine (such as an Epi-Pen) to use if an attack occurs. Anaphylaxis is considered a medical emergency. Failure to get appropriate care can result in shock, cardiac or respiratory arrest, and even death.

    Ultimately, the best way to avoid angioedema is to identify and avoid the allergens that can trigger an allergic response.


    Bernstein, J.; Cremonesi, P.; Hoffmann, T, et al. "Angioedema in the emergency department: a practical guide to differential diagnosis and management". Int J Emerg Med. 2017; 10(1):15. DOI: 10.1186/s12245-017-0141-z.

    Fog Anderson, M.; Longhurst, H.; and Rye Rasmussen, E. " How Not to Be Misled by Disorders Mimicking Angioedema: A Review of Pseudoangioedema." Int Arch Allergy Immunol. 2016;169:163-70. DOI: 10.1159/000445835.