What Causes Angioedema?

What causes angioedema? 

Angioedema is a type of swelling that occurs under the skin's surface and in fatty tissue. It is caused by food allergies, drugs, genetics, weakened immune system or by an unknown cause.
Angioedema is a type of swelling that occurs under the skin's surface and in fatty tissue. It is caused by food allergies, drugs, genetics, weakened immune system or by unknown factors.

Angioedema is swelling that is similar to hives but occurs under the surface of the skin and in fatty tissue. It can affect many different areas of your body, including your face, throat, hands, feet, abdomen, or genitals. 

Angioedema creates firm, thick welts that are often red and painful. This condition may be life-threatening if excessive swelling occurs in your throat. If you’re experiencing these symptoms and struggling to breathe, seek immediate medical attention. 

Angioedema is also known as angioneurotic edema, welts, or, more generally, as an allergic reaction.

Symptoms of angioedema 

Swelling from angioedema can appear suddenly, often without warning. Your skin may swell in one area only or the swelling may spread throughout your body. Sometimes you’ll develop hives or welts that are painful and itchy

Other symptoms of angioedema include:

  • Difficulty breathing
  • Abdominal cramps
  • Swelling around the eyes and mouth
  • Swelling in the lining of the eyes, a condition called chemosis

Types of angioedema

There are five types of angioedema. Swelling can result from an allergic reaction, sensitivity to a certain medication, heredity, or an unknown substance. 

Allergic angioedema

This is the most common type of angioedema and occurs after eating certain foods like shellfish and peanuts. It’s also a reaction to common environmental allergens (substances that can cause an allergic reaction) like pollen and pet dander. 

Drug-induced angioedema

Certain over-the-counter (OTC) and prescription drugs may trigger a reaction, including:

Hereditary angioedema (HAE)

Although it is rare, this condition happens when your body can’t make enough of a specific blood protein called C1 esterase inhibitor. It causes fluid in your blood to transfer to other tissues and creates swelling. This is the most common form of angioedema and affects 85% of people who experience angioedema. 

Hereditary angioedema is passed down through generations, from parents to their children. Kids often experience symptoms before the age of 12.

Acquired angioedema

Another rare form, this type of angioedema occurs in adults over the age of 40. Symptoms are similar to hereditary angioedema, but acquired angioedema isn’t hereditary. It’s typically the result of a weakened immune system.

Idiopathic angioedema

Idiopathic angioedema is angioedema that occurs without a known cause. Doctors often attribute sudden swelling that lasts more than six weeks to the following: 

Causes of angioedema

Doctors believe that most angioedema cases occur when your immune system responds to a foreign invader like an allergen. This causes your body to release histamines and other chemicals into the bloodstream, creating specific symptoms. It can be difficult to pinpoint the exact cause of angioedema. 

Angioedema can result from food or environmental allergens, including:

  • Fish
  • Shellfish
  • Tree nuts or peanuts
  • Milk
  • Eggs 
  • Pet dander
  • Pollen
  • Ragweed
  • Latex
  • Insect bites or stings

When to see the doctor for angioedema

Excessive swelling that comes on suddenly is a cause for concern. Call your doctor if: 

  • Your body isn’t responding to over-the-counter treatments like allergy medication
  • You experience extreme swelling
  • This is the first time you’ve experienced angioedema

Call 911 or go to the emergency room if you experience: 

If you can’t breathe, that’s considered an emergency. Even minor swelling that creates breathing difficulties requires immediate medical attention. 

Diagnosing angioedema

To determine the cause of your angioedema, your doctor will ask questions about your health, symptoms, and family history. If you’ve experienced sudden swelling before, it helps to record the details of those experiences. That way, you’ll remember what happened and may be able to identify commonalities from one episode to the next. 

When you visit your healthcare provider, it’s important to describe all of your symptoms and bring a list of medications you’re taking. Some prescription medications or supplements can make angioedema worse.

Physical exams, allergy skin tests, or blood tests may be necessary to help your doctor determine what is causing your angioedema. 

Treatments for angioedema 

The first course of treatment involves antihistamine medication to alleviate itching, reduce hives, and eliminate swelling. This won’t cure angioedema but will provide temporary relief. Sometimes, you’ll need to take several different medications or multiple doses to reduce your symptoms. 

Common treatments for angioedema include: 

It’s important to work with your doctor to create a treatment plan that relieves your symptoms during an outbreak. In most cases, you can reduce the amount of medication you take when you no longer continue to have symptoms. 


Common Allergies: Symptoms and Signs See Slideshow

American Academy of Allergy, Asthma & Immunology: "Hives (Urticaria) and Angioedema Overview."

Columbia University Irving Medical Center: "Angioedema and Swelling Syndromes."

Mount Sinai: "Angioedema."

National Jewish Health: "Angioedema: Diagnosis."

NHS: "Causes Angioedema."

Penn Medicine: "What is Angioedema?"

UC San Diego Health: "Angioedema."

US Hereditary Angioedema Association: "Types of Angioedema."