Causes

Angioedema can have several different causes, but in many cases the exact cause is unknown.

Some of the main causes of angioedema are outlined below.

Allergies

Angioedema is oftenthe result of an Indoor allergy .

This is where the body mistakes a harmless substance, such as a certainfood,for something dangerous.Itreleases chemicals into the body to attackthe substance, which cause the skin to swell.

Angioedema can be triggered by an allergic reaction to:

• certain types of food particularly nuts, shellfish, milk and eggs
• some types of medicationincluding some antibiotics , aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) , such as ibuprofen
• insect bites and stings particularly wasp and bee stings
• latex a type of rubber used to make medical gloves, balloons and condoms

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

Medication

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".

Genetics

Rarely, angioedema occurs because of a genetic fault that you inherit from your parents.

The fault affectsthe gene responsible for the production ofa substance calledC1 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 a50% 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 unknownproblem with the immune systemmight cause it to occasionallymisfire.

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 aclear cause is known as"idiopathic angioedema".