What causes angioedema?

Angioedema is swelling under your skin due to fluid leaking from your blood vessels. It often occurs due to allergies or medications but may also be hereditary.
There are several causes of angioedema, though in some cases, the cause is unknown.
Drug-induced angioedema
Some medications can cause angioedema. Angiotensin converting enzyme (ACE) inhibitors are medications for blood pressure and heart problems. About 1 in 200 people who take ACE inhibitors experience swelling.
Usually, the angioedema appears within the first months of taking the medication. Sometimes, the swellings only appear months or years later or when your dosage is increased. Experts say that it’s unclear why some people get angioedema after taking ACE inhibitors.
Angioedema caused by these medications usually appears around your face, throat, and tongue. Outbreaks are not accompanied by hives (urticaria) and also aren’t painful or itchy. When you stop taking the medication, the swelling can take a few weeks to go away.
Other medications that may cause angioedema include:
- Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen
- Angiotensin-2 receptor blockers (ARBs), which are used to treat high blood pressure. This category also includes losartan, olmesartan, and valsartan.
About 0.1% to 0.3% of people get angioedema from taking nonsteroidal anti-inflammatory drugs. More than half of these are reactions to ibuprofen.
Some foods can trigger allergic angioedema. Sometimes, eating a small amount can suddenly cause angioedema, but with other foods, like strawberries, a large amount has to be eaten to cause swelling. Potentially triggering foods include:
- Nuts
- Fruits
- Fish
- Eggs
- Shellfish
Hereditary and acquired angioedema
Hereditary angioedema is due to a genetic disorder. This disorder causes a deficiency of a protein known as C1 inhibitor, which is part of your immune system.
Acquired angioedema is different from hereditary angioedema. This rare disorder develops when some cancers or autoimmune disorders cause a deficiency of C1 inhibitor.
Unknown causes
For many people, it’s unclear what causes angioedema. This is known as idiopathic angioedema.
Some triggers that may cause swelling include:
Symptoms of angioedema
The main symptom of angioedema is swelling. This can appear suddenly or take a few hours to develop. It usually lasts a few days. In many people, the swelling appears, along with itchy raised rashes (hives).
Visible swelling often affects your:
- Eyes
- Lips
- Tongue
- Feet
- Hands
- Genitals
Other less common symptoms include:
- Abdominal pain
- Diarrhea
- Dizziness
- Fainting
- Difficulty breathing
- Irritated and red eyes (conjunctivitis)
For hereditary and acquired angioedema, there’s swelling but no hives. Swollen areas may be slightly painful but not itchy.
The membranes lining your mouth, airways, and throat may also swell. You may make a gasping sound when breathing in. Seek immediate medical help if you have this type of swelling.
You may also have swelling in the membranes that line your digestive tract. This leads to cramps, nausea, and vomiting.
For most people, angioedema eventually disappears, but for some people, it’s a recurrent problem that reappears throughout your life.
Is angioedema serious?
Angioedema doesn’t cause damage to your internal organs, but it can be life-threatening if your tongue or throat swells up badly and causes breathing problems. Swelling that causes breathing problems is rare, though, even in people with recurrent angioedema.
Treatment for angioedema
There’s no known cure for angioedema, but you may be able to prevent further episodes with treatment.
The main goal of treatment is to reduce swelling and discomfort. Treatment for angioedema depends on its cause.
Allergic or idiopathic angioedema
If the angioedema is due to an allergy or an unknown cause, treatment includes:
- Avoid activities or substances that trigger your symptoms.
- Antihistamines may help reduce swelling and relieve itching.
- If swelling is severe, your doctor may prescribe steroid medication. Steroids can have serious side effects, so they should only be taken for short periods.
ACE inhibitor-related angioedema
If angioedema is caused by an ACE inhibitor, your symptoms usually go away 24 hours to 48 hours after stopping the medication.
Hereditary angioedema
Medication can help prevent attacks. Stanozolol and danazol are synthetic male hormones that can boost your body’s levels of C1 inhibitor. These drugs may not be as effective for acquired angioedema.
Another drug that is used to prevent attacks for those age 12 and up is lanadelumab. This is a monoclonal antibody drug administered via injection.
Emergency treatment
If you have trouble breathing or swallowing, you need immediate medical help. Doctors will open your airway in one or more ways:
- Insert a breathing tube through your nose or mouth and into your windpipe
- Make a small cut in the skin over your windpipe to insert the tube
- Inject epinephrine into your muscle or under your skin to reduce swelling
If you have severe reactions, you should carry an epinephrine auto-injector and use it immediately when you have a reaction. Go to an emergency room to be checked and treated.

SLIDESHOW
Rosacea, Acne, Shingles, Covid-19 Rashes: Common Adult Skin Diseases See SlideshowAustralasian Society of Clinical Immunology and Allergy: "Angioedema."
Journal of Pharmacy Technology: "Recurrent Angioedema Following Repeat Exposure to NSAID."
Medscape: "Angioedema."
Merck Manual: "Angioedema."{Merck Manual: "Hereditary and Acquired Angioedema."
NHS: "Causes Angioedema," "Symptoms Angioedema," "Treatment Angioedema."
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