Angioedema is often the result of an allergic reaction.

It can be triggered by an allergic reaction to:

Angioedema caused by allergies is known as "allergic angioedema".


Some medicines can cause angioedema – even if you're not allergic to the medication.

The swelling may occur soon after you start taking a new medication, or possibly months or even years later.

Medications that can cause angioedema include:

  • angiotensin-converting enzyme (ACE) inhibitors, such as enalapril, lisinopril, perindopril and ramipril, which are used to treat high blood pressure 
  • ibuprofen and other types of NSAID painkillers 
  • angiotensin-2 receptor blockers (ARBs), such as andesartan, irbesartan, losartan, valsartan and olmesartan – another medication used to treat high blood pressure

Angioedema caused by medication is known as "drug-induced angioedema".


Rarely, angioedema occurs because of a genetic fault.

The fault affects the gene responsible for the production of a substance called C1 esterase inhibitor. If you don't have enough of this, the immune system can occasionally "misfire" and cause angioedema.

The swelling may happen randomly, or it may be triggered by:

  • an injury or infection
  • surgery and dental treatment
  • stress
  • pregnancy
  • certain medications, such as the contraceptive pill

How often the swelling occurs can vary. Some people experience it every week, while in others it may occur less than once a year.

Angioedema caused by a genetic fault is known as "hereditary angioedema". If you have it, you have a 50% chance of passing it on to your children.

Unknown cause

In many cases, it's not clear what causes angioedema.

One theory is that an unknown problem with the immune system might cause it to occasionally misfire.

Certain triggers may lead to swelling, such as:

  • anxiety or stress
  • minor infections
  • hot or cold temperatures
  • strenuous exercise

In very rare cases, the swelling may be associated with other medical conditions, such as lupus or lymphoma (cancer of the lymphatic system).

Angioedema without a clear cause is known as "idiopathic angioedema".




The treatment for angioedema depends on what's causing it.

There are several different types of angioedema, each of which has a different cause.

Angioedema can usually be treated at home, although severe cases may need to be treated in hospital.

Allergic and idiopathic angioedema

Allergic angioedema and idiopathic angioedema are usually treated in a similar way.

Avoiding triggers

Avoiding particular substances or activities that trigger your symptoms may help reduce your chances of experiencing swelling.

For example, if you're allergic to a certain type of food, it can help to check the ingredients in food you buy and be careful when eating out.

Read about preventing allergic reactions for more advice.

Antihistamines and steroid medication

Your GP may suggest taking antihistamines to reduce swelling when it occurs.

Antihistamines work by blocking the effects of histamine, one of the chemicals responsible for the swelling. Some types can be bought in pharmacies and supermarkets without a prescription.

Some antihistamines can make you feel drowsy, so it's best to take non-drowsy medications such as cetirizine and loratadine if your symptoms occur during the day.

Some antihistamines can make you feel drowsy. Avoid driving, drinking alcohol or operating dangerous machinery if you experience this.

Other side effects of antihistamines can include:

If the swelling is severe, your GP may prescribe a short course of steroid medication. This is a powerful medication that's only used for short periods because it can have troublesome side effects.

Adrenaline auto-injectors

If you have a particularly serious allergy, you may be given adrenaline auto-injectors to use if you experience a severe allergic reaction (anaphylaxis).

There are several types of auto-injector, which are used in slightly different ways.

Read about preventing anaphylaxis for more information.

Drug-induced angioedema

If a certain medication you're taking is thought to be responsible for your angioedema, your doctor will usually advise stopping it.

They can prescribe a different medication for you to take instead.

This is usually all that needs to be done. Tell your doctor if your symptoms continue or come back after switching medication.

Hereditary angioedema

Hereditary angioedema can't be cured, but medications can help prevent and treat the swelling.

Preventing swelling

Medications called danazol and oxandrolone can help reduce the chances of swelling occurring if you have hereditary angioedema.

These medicines boost the levels of C1 esterase inhibitor in your blood. Low levels of this substance are what causes the swelling.

Side effects of these medications can include:

A medication called tranexamic acid may sometimes be used as an alternative, particularly in children and women. This causes fewer side effects, but may not be as effective in preventing swelling.

Treating swelling

Two main treatments can be used to treat swelling caused by hereditary angioedema:

  • icatibant – a medication given by injection that blocks the effects of some of the chemicals responsible for the swelling
  • C1 esterase inhibitor replacement – a treatment given by injection that boosts the levels of C1 esterase inhibitor in your blood

Occasionally, C1 esterase inhibitor replacement may also be used shortly before surgery or dental treatment, as it can reduce the risk of these triggering swelling.

You may be given a supply of medication to keep at home and be taught how to give the injections yourself.



Angioedema is self-limited, localized subcutaneous (or submucosal) swelling, which results from extravasation of fluid into interstitial tissues.

Angioedema may occur in isolation, accompanied by urticaria, or as a component of anaphylaxis.






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A 37-year-old man has recently been diagnosed with systemic hypertension. He is prescribed lisinopril as initial monotherapy. He takes this medication as prescribed for 3 days and, on the third day, notes that his right hand is swollen, mildly itching, and tingling. Later that evening, his lips become swollen and he has difficulty breathing. Which of the following statements accurately describes this condition?

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