Angioedema is swelling of the deeper layers of the skin. The swelling is often severe and is caused by a build-up of fluid. The symptoms of angioedema can affect any part of the body, but they usually affect the:
Medication, such as antihistamines and oral steroids (steroid tablets), can be used to relieve the swelling. In particularly troublesome cases they can also prevent symptoms from occurring in the first place.
See Angioedema - treatment for more information.
Many people with angioedema also have another condition called urticaria, which is also known as hives, welts or nettle rash. This is a raised, red and itchy rash that appears on the skin.
See the Health A-Z topic about Urticaria for more information about the condition.
Types of angioedema
There are four main types of angioedema:
allergic angioedema – the swelling is caused by an allergic reaction, such as a reaction to peanuts
idiopathic angioedema – there is no known cause for the symptoms of swelling (although certain factors, such as stress or infection, may trigger the symptoms)
drug-induced angioedema – the swelling is a side effect of certain medications
hereditary angioedema – the swelling is caused by ‘faulty’ genes that are inherited from a person’s parents; unlike the other types of angioedema, people with hereditary angioedema do not experience urticaria
Allergic angioedema is thought to be the most common type of angioedema. It often affects people with food allergies. Food allergies are thought to affect 5-8% of children and 1-2% of adults.
Very severe allergic reactions can cause swelling of the throat, which can cause breathing difficulties and a sudden fall in blood pressure. This type of extreme allergic reaction is known as anaphylaxis and is a medical emergency.
In most cases, allergic angioedema is an acute (short-lived) condition because after a person has identified the substance (allergen) responsible for triggering the allergic reaction, they can avoid it in the future.
It is difficult to estimate how common acute idiopathic angioedema is because many cases may be misdiagnosed as allergic angioedema.
However, chronic (long-lasting) idiopathic angioedema is uncommon. It is estimated to affect around 1 in 2,000 people. People with chronic idiopathic angioedema may also experience symptoms of urticaria.
Stress is the most common cause of idiopathic angioedema, but it can also be caused by:
- thyroid gland problems
- a deficiency of iron, vitamin B12 or folic acid
- infections, particularly dental, sinus and gallbladder infections.
Drug-induced angioedema is an uncommon side effect of certain medications. Symptoms of angioedema can be triggered by a type of medication known as angiotensin-converting enzyme (ACE) inhibitors, which are used to treat high blood pressure (hypertension). This can come on at any time after the medication is started. It can last for up to three months after the medication has stopped.
Drug-induced angioedema is not the same as having an allergic reaction to certain medications, such as penicillin. This is because the underlying mechanisms are very different. It is often days and, in many cases, years before you notice a reaction, but an allergic reaction develops within a few minutes to an hour.
It is estimated that 1 in 500 people who are being treated with ACE inhibitors will develop angioedema.
Hereditary angioedema is the rarest type of angioedema, estimated to affect 1 in 25,000 people.
Hereditary angioedema is caused by the lack of a protein in the blood called C1-esterase inhibitor. Unlike allergic angioedema, the swellings tend to come on slowly. It can affect the throat and the bowel, and cause abdominal (tummy) pain.
Hereditary angioedema attacks tend to begin after puberty, and they can occur with any frequency. They can be triggered by:
- trauma or infection
- the oral contraceptive pill
Specific medication is available to prevent and treat attacks of hereditary angioedema.
How common is angioedema?
It is estimated that 10-20% of people are affected by angioedema at some point during their life.
The outlook for allergic angioedema is generally good. The symptoms usually pass within one to three days. However, the condition can be unpredictable. A recurrence of symptoms is common.
The outlook for idiopathic angioedema is mixed. While the symptoms do not usually pose a serious risk to health, the frequent reoccurrence of symptoms can be frustrating and unpleasant to live with.
Drug-induced angioedema can usually be successfully treated by using an alternative medication to treat whatever underlying condition you have.
The outlook for hereditary angioedema is generally good because a number of different medications can successfully prevent the onset of symptoms.
Last updated: 07 June 2012
Continue to next section: Symptoms of angioedema