Angioedema

What is angioedema?

Angioedema is sudden swelling beneath the surface of the skin, most often affecting the lips, eyelids, hands, feet or genitals. It's frequently caused by an allergic reaction, but can also happen without any obvious cause, as a medication side effect, or, rarely, as an inherited condition.

What are the symptoms of angioedema?

The main symptom is swelling, which can affect:

• the face, particularly the lips, tongue and eyelids
• the hands or feet
• the genitals
• the lining of the bowel, which can cause stomach pain, nausea or diarrhoea

The swollen area may feel hot, tingly or painful. If an allergic reaction has caused it, you'll often also have a raised, itchy rash (hives), though it's possible to have angioedema without any rash at all. Swelling usually develops quickly and settles within a few hours to around 2 to 3 days.

Rarely, swelling spreads to the throat and airway, causing breathing difficulties. This is a medical emergency requiring immediate treatment. See the "when should you see a doctor" section below for the specific warning signs to watch for.

What causes angioedema, and who's at risk?

Angioedema happens when fluid leaks out of small blood vessels and builds up in the tissue beneath the skin. There are several possible triggers:

• an allergic reaction to food, medicines, latex, insect stings or bites, or animal dander, usually causing swelling within minutes to a couple of hours
• a non-allergic reaction to a medicine, most commonly ACE inhibitors (used for high blood pressure), where swelling can develop weeks or months after starting the drug rather than right away
• other medicines, including anti-inflammatory painkillers such as ibuprofen or aspirin
• vibration, such as from motorcycling, running or using powered garden tools, in certain sensitive individuals
• a rare inherited condition (hereditary angioedema), affecting around 1 in 50,000 people, caused by a faulty gene affecting a blood protein called C1-inhibitor
• a very rare acquired form linked to conditions such as lymphoma or lupus

In many cases, no specific cause is ever found (idiopathic angioedema). Angioedema is common overall, affecting an estimated 10–20% of people at some point in their lives, and ACE inhibitors alone account for up to 30% of angioedema-related emergency department visits.

Are there different types of angioedema?

Angioedema is generally grouped into 5 types, based on its cause:

• acute allergic angioedema, from an allergic reaction to a food, medicine or other substance
• non-allergic angioedema, a side effect of certain medicines, most often ACE inhibitors
• idiopathic angioedema, ongoing swelling with no identifiable cause
• hereditary angioedema, a rare and potentially serious inherited form
• acquired angioedema, a very rare form linked to conditions such as lymphoma or lupus

Hereditary angioedema behaves differently from the other types. It doesn't respond well to antihistamines or steroids and needs its own specific treatments. It tends to run in families and can be more severe in women than men.

How is angioedema diagnosed?

Your doctor will examine the swollen area and ask about your symptoms, including when the swelling started, anything you may have eaten or were exposed to beforehand, your medications and supplements, whether you've had similar swelling before, and whether other family members have had it too.

If an allergy is suspected, you may be offered a skin prick test or a blood test to check your immune response to a specific allergen. If there's no obvious trigger, blood tests can check your C1-inhibitor levels and function, since low or abnormal levels point towards a hereditary or acquired cause rather than an allergic one. If your throat or neck is affected, a doctor may also examine your airway directly using a small camera.

How is angioedema treated?

Mild angioedema affecting a small area may not need any treatment and can settle by itself.

Non-emergency treatment

• identifying and avoiding the trigger, such as a specific food or medicine
• switching to an alternative medicine if a drug is thought to be the cause, done in discussion with your doctor rather than stopping it yourself
• antihistamine medicine, such as cetirizine, fexofenadine or loratadine
• steroid tablets, such as prednisolone, for more significant swelling
• ice packs or a cool shower, which can help reduce swelling

If you have frequent allergic reactions, a medicine that reduces the risk of future reactions may be considered.

Treatment for hereditary or recurring angioedema

Hereditary angioedema doesn't respond well to antihistamines or steroids, so it needs its own approach: medicines that either replace the missing C1-inhibitor protein or block the substances that cause the swelling, used either to treat an attack as it happens or regularly to help prevent attacks. If you carry an adrenaline auto-injector for a known severe allergy, use it as advised if you think you're having a severe reaction while waiting for emergency help.

Emergency treatment

If swelling is severe or widespread or affects your lips, tongue or throat, you'll need emergency treatment in hospital. This may include medicines to bring the swelling down quickly and, in severe cases where the airway is at risk, a breathing tube to keep it open while the swelling settles.

When should you see a doctor?

See a GP, or call 111, if part of your body suddenly becomes swollen, such as your hands, feet or genitals, especially if it keeps happening or you don't know the cause.

Call 999 or go to A&E immediately if you or someone you're with has any of the following:

• sudden swelling of the lips, mouth, throat or tongue
• fast or laboured breathing, wheezing, or a choking or gasping sensation
• a tight throat or difficulty swallowing
• skin, tongue or lips turning blue, grey or pale (on black or brown skin, this can be easier to see on the palms or soles)
• sudden confusion, drowsiness or dizziness
• fainting, or being unable to wake someone up
• in a child, floppiness or not responding normally

These can be signs of a serious allergic reaction and need immediate treatment in hospital.