How Contact Dermatitis and Angioedema Are Different

young problematic skin with dermatitis
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Patients are often referred to an allergist for an evaluation of an “allergic reaction." Many of these people have had facial swelling that their referring physician has diagnosed as angioedema. As a result of their symptoms, the person was likely treated with antihistamines, corticosteroids, and possibly even injectable epinephrine.

Differences in Symptoms

The difference between angioedema and contact dermatitis are often subtle, and it takes someone with years of training and experience to know the differences between these two similar conditions.

After all, both can cause severe swelling of the face, eyes, and lips, both can cause a person to seek emergency medical care based on their symptoms, and both often result in a person being referred to an allergist.

Here are the major differences in how the symptoms of contact dermatitis differ from angioedema:

  1. Contact dermatitis is usually red and itchy. People with contact dermatitis may even break the skin (excoriate) as a result of scratching. Angioedema is not red, and not itchy. Rather, angioedema may sting, burn, feel numb, or possibly even painful. A person with angioedema will not excoriate the skin.
  2. Contact dermatitis is usually symmetrical, or at least more symmetrical, than angioedema. Facial swelling from contact dermatitis usually involves both eyes and/or all of the upper and/or lower lips. Angioedema tends to be more asymmetrical, meaning that it often involves only one eye and one part of the upper or lower lip.
  1. When the swelling from contact dermatitis resolves, which may take many days to occur, the skin appears dry, flaky or “chapped.” The swelling from angioedema often resolves in a day or two and the skin is perfectly normal in appearance after the swelling resolves.
  2. Angioedema is often, but not always, associated with urticaria (hives). It is useful to know if a person also had an itchy rash on the body that was associated with the facial swelling. Similar to angioedema, when the rash from urticaria resolves, the skin is completely normal without dryness, flaking or chapping.

    These differences go back to how the actual disease processes occur. Contact dermatitis is caused by delayed type hypersensitivity, resulting in T cells (a type of white blood cell) infiltrating the skin. This causes more chronic changes that last for many days, cause significant itching, and leave behind residual changes and damage to the skin when the swelling has resolved.

    Angioedema, on the other hand, is caused by histamine release into the skin of certain tissues (lips, eyes, tongue, throat, genitals). These tissues will swell and not itch, while histamine release into other areas of the skin will itch and form hives. Histamine causes blood vessels to dilate, resulting in fluid extravasation into surrounding tissue. Since histamine only lasts for a few minutes on the skin, hives only last for a short period of time (usually minutes to a few hours). Angioedema lasts for a little longer (hours to a day or two) because the fluid released from blood vessels as a result of histamine can take time to be reabsorbed into the circulation.


    Beltrani VS, Bernstein IL, Cohen DE, Fonacier L. Contact Dermatitis: A Practice Parameter. Ann Allergy Asthma Immunol. 2006;97:S1-38.

    Charlesworth E. Differential Diagnosis of Angioedema. Allergy and Asthma Proceedings. 2002;23(5):337-339.

    Practice Parameters for Disease Management: Acute and Chronic Urticaria and Angioedema. Ann Allergy. 2000; 85: S525-44.