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Angioedema: Causes of the Swelling

How to treat angioedema when it happens and try to prevent it.
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Last updated May 6, 2024

Angieoedema quiz

Take a quiz to find out if you have angieoedema.

What is angioedema?

Angioedema is sudden swelling of the deep layer of your skin in one part of your body—most often in the face, mouth, or throat. But it can also affect the hands and feet, genitals, and the bowel wall.

It is often an allergic reaction (to a food or medication, for example). But it may develop as a response to another disorder (called acquired). In rare cases, it is genetic (hereditary). Sometimes it happens for no known reason (idiopathic). When an allergic reaction, it is not usually a body-wide reaction like the life-threatening anaphylaxis, but just involves one part of the body.

Allergic and idiopathic angioedema are treated like you treat an allergic reaction. But there are no proven ways to reduce the swelling for hereditary or acquired angioedema.

What are the signs and symptoms of angioedema?

Dr. Rx

Those with recurrent unexplained abdominal symptoms may have underlying angioedema. You must advocate for yourself because angioedema is not common, so understandably, your physician may not consider it. —Dr. Chandra Manuelpillai

The most common symptom is swelling in one area, like the lips or eyes. Other symptoms depend on where the swelling is. Swelling often peaks quickly then slowly resolves. So once the swelling starts going down, it is rare that it worsens.

Main symptoms

  • Swelling in one part of your body: face, mouth, throat, extremities, genitals, or bowel wall.

Other symptoms

These depend on where your swelling is.

  • Eye: tearing or vision changes.
  • Airway (mouth, throat): stridor (whistling sound with breathing), trouble breathing, changes in voice, and/or trouble handling saliva.
  • Bowel wall: stomach pain, nausea, vomiting, diarrhea, and cramping.

What causes angioedema?

Angioedema is the swelling of the deep layer of the skin. It is most often an allergic-type reaction to food or medications.

Drugs that are more likely to cause it include the class of blood pressure medicine called ACE inhibitors (such as lisinopril), nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen (Advil, Motrin) and aspirin.

Pro Tip

If an EpiPen is part of your treatment plan, it is very important to always have one available. This means carrying one on you at all times, giving one to schools, caretakers, coaches and keeping an extra EpiPen at home and in your car. —Dr. Manuelpillai

Angioedema treatment

Immediately call 911 or go to the ER if the swelling involves the airway (lips, mouth, tongue, throat), or you’re having difficulty breathing, chest pain, or dizziness. It can be life threatening.

If there’s a risk of anaphylaxis (a life-threatening body-wide reaction), then epinephrine (EpiPen) should be used right away. And you should go to the ER. If you do not have an EpiPen and suspect anaphylaxis or symptoms continue to worsen, call 911.

You will likely be admitted to the hospital if the swelling involves your mouth or throat.

Treatment is based on the cause and severity of symptoms.

For most cases, allergy medications are helpful. This includes antihistamines and steroids.

If symptoms continue or get worse despite taking allergy medications, then you may have hereditary or acquired angioedema. There are no proven treatments for either, but there are some your doctor may try.

Treating idiopathic angioedema often includes daily antihistamines. Speak to your doctor about how to treat it. Typically, when there is new swelling, you take the over-the-counter antihistamine diphenhydramine (Benadryl) and the prescription prednisone. But this treatment should be managed by your doctor.


Before starting any new medications or treatments, discuss with your doctor (and pharmacist) dosage, side effects, and any medication interactions.

  • Antihistamines: Some may cause drowsiness; most are over-the-counter. They include diphenhydramine (Benadryl), loratadine (Claritin), cetirizine (Zyrtec), and others.
  • Steroids: Prednisone by mouth or intravenously (IV).
  • Epinephrine—if there is a possibility of swelling of the airways or body-wide reactions. EpiPen or Junior EpiPen for children (if available). Call 911 after using.
  • Bronchodilator (albuterol) with an inhaler or nebulizer if coughing, wheezing, or shortness of breath.

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Children and angioedema

Angioedema is more common in adults than children. However, the hereditary type often first occurs during childhood. Although it is rare.

Symptoms are the same. For those areas that cannot be seen (throat, bowel wall), you may notice your child drooling or spitting up more, or has repeated coughing or hoarseness.

Causes are also similar. Though for adults the most common cause is medications, while children are more likely to have reactions to food.

If a child has a body-wide reaction or trouble breathing, they should have access to an EpiPen or EpiPen Jr. in case it happens again. They should also see an allergist. It is important to inform all those involved in your child’s care of the risk of angioedema and to have a treatment action plan in place.

Follow up

Pro Tip

Angioedema is not well understood. However, there is some new research on whether medical cannabis may be used to treat hereditary angioedema. Also, the role of stress and one’s response to stress is starting to be correlated with hereditary angioedema attacks. —Dr. Manuelpillai

Swelling usually peaks quickly. Within minutes to hours for allergic reactions. Hours-to-days for hereditary or acquired angioedema. Then it slowly gets better.

If there is any concern of a life-threatening reaction or possible rebound allergic reaction, you should be given a prescription for an EpiPen and see an allergist.

Since angioedema is not well understood, it is important to follow up with those who specialize in the condition. It could be an allergist or immunologist. You may also want to discuss a referral to an angioedema-focused center.


If the swelling is caused by a trigger—a medication or food—then avoiding the trigger is the main goal of prevention.

But in cases where the cause is not clear, you may need to take antihistamines daily and see a specialist such as an allergist or immunologist.

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The stories shared below are not written by Buoy employees. Buoy does not endorse any of the information in these stories. Whenever you have questions or concerns about a medical condition, you should always contact your doctor or a healthcare provider.
Dr. Le obtained his MD from Harvard Medical School and his BA from Harvard College. Before Buoy, his research focused on glioblastoma, a deadly form of brain cancer. Outside of work, Dr. Le enjoys cooking and struggling to run up-and-down the floor in an adult basketball league.

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