Angioedema is a form of swelling in the deep part of the skin’s inner layer and below, and it may become severe. In some cases, this swelling occurs along with the appearance of hives. This is why angioedema is sometimes referred to as “giant hives.”

Hives are itchy and raised, red welts that develop on the surface of the skin, involving only the two skin layers. Urticaria is another word for hives.

Both angioedema and hives can be caused by an allergic reaction or intolerance to food, a side effect or allergy to a medication, or an allergen in the surrounding environment, such as pollen, pet dander, and venom from insect bites.

In very rare cases, the swelling can be a symptom of a more serious health condition, such as non-Hodgkin’s B-cell lymphoma. Some areas of the body, such as the eyelids, lips, and tongue, are more prone to angioedema than others.

When angioedema is passed from a parent to a child through genetic transmission, the condition is known as hereditary angioedema. Hereditary angioedema has different causes than acquired angioedema, but in either case, the symptoms and treatment approach will be similar.

Angioedema may be part of a serious medical condition. When due to an acute allergic reaction, chances for recovery are very favorable with prompt treatment. If someone has only mild angioedema, it may resolve on its own without any therapy.

The most common symptom of angioedema is swelling with a red colored rash beneath the surface of the skin. It may occur in a localized area on or near the feet, hands, eyes, or lips.

In more severe cases, the swelling can spread to other parts of the body. Angioedema may or may not be accompanied by swelling and welts on the surface of the skin.

Additional symptoms of angioedema may include abdominal cramping. In rare cases, people with angioedema may experience a swollen throat, hoarseness, and difficulty breathing. Angioedema may or may not itch.

Call 911 or go to an emergency room right away if you’re having trouble breathing. This may be a sign of a serious medical condition that requires prompt treatment.

Acute angioedema is commonly the result of an allergic reaction. When you have an acute allergic reaction, your body releases histamine, which makes your blood vessels dilate and leak fluid.

The following allergens can trigger angioedema:

  • insect bites
  • pollen
  • poison oak or ivy
  • latex
  • animal dander
  • medication
  • certain types of foods

Additionally, certain medications can cause nonallergic angioedema.

Angioedema may also develop as a result of an infection or illness, such as lupus (SLE) or leukemia. These would be examples of acquired angioedema.

Hereditary angioedema occurs in people with a family history of the condition, due to an inherited genetic mutation.

Certain factors can increase your risk of developing angioedema. These include:

  • a previous occurrence of angioedema or hives
  • a previous allergic reaction
  • a family history of angioedema or hives
  • sudden temperature changes
  • stress or anxiety
  • certain medical conditions

Your doctor will perform a physical exam and ask you about your symptoms and past medical history. During the exam, your doctor will examine your areas of swelling and your welts, if any are present. They may also listen to your breathing to see if your throat has been affected.

It’s important to tell your doctor if you’ve recently been exposed to certain substances that have previously triggered an allergic reaction in you. This may help your doctor determine the specific cause of your reaction.

Your doctor will perform a series of blood tests if hereditary or acquired angioedema is suspected. These may include:

These tests measure the levels or function of certain proteins in the blood. Abnormal results can also be associated with a health problem related to underlying autoimmune disease.

People with mild symptoms of angioedema may not need treatment. However, those with moderate or severe symptoms may require certain medications to help relieve intense swelling. These medications can include:

  • epinephrine, if due to acute allergic reaction
  • antihistamines, such as loratadine and cetirizine, if due to an allergic reaction or angioedema where the cause is unknown
  • glucocorticosteroid, such as prednisone or Solu-Medrol, if due to acute allergic reaction

Treatment options available specifically for hereditary or acquired angioedema include the following:

  • purified human C1 esterase inhibitor
  • fresh frozen plasma
  • ecallantide
  • icatibant

It should be noted that fresh frozen plasma treatment isn’t approved by the Food and Drug Administration (FDA) for this purpose and is used off-label.

Certain home remedies may also help relieve symptoms. These include:

  • applying cool, wet compresses to help soothe the skin and prevent scratching
  • wearing loose cotton clothing to avoid further skin irritation

If a medication is causing you to have angioedema, your doctor may have you switch a different one.

In many cases, angioedema is a harmless condition that will disappear within a few days.

However, angioedema can be dangerous when the swelling is severe and occurs near the throat. A swollen throat or tongue can block your airway and make it very difficult to breathe.

Severe angioedema may be due to anaphylaxis, a life threatening, severe acute allergic reaction. In such severe cases, you should seek emergency medical help immediately.

The best way to prevent allergic angioedema is to avoid known and suspected allergens. You should also try to avoid any known triggers that have caused angioedema for you in the past.

Taking these preventive measures can help lower your risk of having another episode in the future.