Angioedema

What it is

Angioedema is swelling below the surface of the skin and fatty tissue, and the swollen areas may be painful.² AAAAI defines it as swelling in the deep layers of the skin, often seen with hives, also called urticaria.¹ It can also happen without hives.²

The word itself is a medical term to describe swelling, and there are several different ways that swelling can occur.² ACAAI says angioedema can be caused by allergic reactions, by drugs, or by a hereditary deficiency of some enzymes.⁵

Angioedema is called acute when it lasts only a short time, and acute angioedema is commonly caused by an allergic reaction to drugs or foods.¹ Chronic recurrent angioedema returns over a long period of time, with each episode lasting hours to several days.³

Symptoms

The swelling usually shows up in the face, throat, hands and feet.² It often involves soft tissues such as the eyelids, mouth or genitals, and on the face it often appears around the eyes, cheeks or lips.³ This deeper swelling can also occur inside the bowels or throat.³

ACAAI’s list of possible signs includes swelling in the eyes or mouth, swelling of the hands, feet or throat, difficulty breathing, stomach cramps, and swelling of the lining of the eyes.⁵

ACAAI notes that angioedema can be mistaken for hives or can occur with them.⁵ Hives are itchy, red and white raised bumps or welts that can appear anywhere on the body, while angioedema is swelling without itch.³

AAAAI says to talk to your doctor if swelling occurs without hives, because this may suggest a special situation that needs more evaluation.² Hereditary angioedema, for example, does not include hives.³

What triggers it

Foods are one common allergic cause of acute angioedema.³ FDA lists face, tongue or lip swelling, and swelling of the throat and vocal cords, among the possible reactions to a food allergy, and says symptoms may appear from within a few minutes to a few hours after eating.⁷ The major food allergens in the US are milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat, soybeans and sesame.⁷

With insect stings, most people who are stung get redness, swelling and itching at the site.⁸ Swelling in the throat or tongue after a sting is a different matter: it is among the possible signs of anaphylaxis, which is a medical emergency.⁸

AAAAI names aspirin, NSAIDs such as ibuprofen, and ACE inhibitors, a class of blood pressure drugs, among the causes of swelling without hives.² The generic names of ACE inhibitors end in “pril,” such as lisinopril, and they can cause swelling at any time, even after years of use.² Swelling without hives can also be spontaneous, from an unknown cause or an autoimmune one.² When angioedema keeps coming back over a long period, most cases do not have an identifiable cause.³

Hereditary angioedema (HAE) is a rare genetic disorder.² People with it have either a low level of a blood protein called C1-INH, or C1-INH that does not work properly.⁴ When this protein does not work properly, fluids can move out of the blood and into tissues to cause swelling.² HAE is estimated to affect 1 in 50,000 people worldwide, and one altered copy of a gene is enough to cause it, though some cases come from a new gene change in people with no family history.⁶

HAE swelling most often affects the limbs, face, intestinal tract and airway, and episodes in the intestinal tract cause severe abdominal pain, nausea and vomiting.⁶ Most attacks are difficult to predict, and possible triggers include anxiety, surgery, dental procedures, some drugs, and illnesses such as colds and flu.⁴ A related condition, acquired angioedema, is a form of C1 inhibitor deficiency that can occur in certain diseases.²

When to see an allergist

Throat swelling can be life threatening and requires immediate medical attention.² ACAAI says any swelling in the throat, or any other symptom that restricts breathing, requires immediate emergency care, and that swelling of the tongue or lips or trouble breathing can be early symptoms of anaphylaxis.⁵ In HAE, swelling in the airway can restrict breathing and lead to life-threatening obstruction of the airway.⁶

If you have symptoms of angioedema, AAAAI says an allergist can help, because allergists have advanced training and experience to find out what is causing symptoms.¹ ACAAI says the best way to identify your symptoms is to talk to an allergist who can diagnose both hives and angioedema.⁵ For chronic hives, the allergist will ask about your and your family’s medical history and the substances you are exposed to at home and at work.⁵ The allergist may also use skin, blood and urine tests to identify the cause of hives.⁵ After a serious reaction to a sting, AAAAI says to make an appointment with an allergist.⁸

If you take an ACE inhibitor and develop angioedema, AAAAI says it is important to consult your doctor.³ Where HAE is possible, AAAAI says it is important to see a specialist to screen for HAE and other genetic conditions.³ Because HAE is rare, doctors often first rule out more common conditions with similar symptoms.⁴ Along with a physical exam and medical history, HAE is diagnosed by measuring the level and function of C1-INH in the blood.⁴

Understanding the mechanism behind the swelling, or the specific disease causing it, is important in figuring out the best treatment, so talk to an allergist about yours.²