Angioedema is usually diagnosed by your doctor examining the affected skin and discussing your symptoms.

It can be difficult to find the exact cause and identify which type of angioedema you have. There is no single test available, but you may have allergy tests or blood tests if a specific cause is suspected.

Allergic angioedema

You're likely to be asked if you have recently been exposed to any allergy-causing substances, such as nuts or latex. You may also be asked whether you have a history of other allergic conditions, such as urticaria (hives) or asthma. People with an allergic condition often develop other allergic conditions.

Tell your doctor about any medications you are taking, including over-the-counter medication, such as painkillers, herbal supplements and vitamins.

Your GP may recommend that you keep a diary of your exposure to possible irritants – or a food diary, if a food allergy is suspected.

If allergic angioedema is suspected, you are likely to be referred to a specialist allergy or immunology clinic for further testing. Tests may include:

• a skin prick test – your skin is pricked with a tiny amount of the suspected allergen to see whether there is a reaction
• a blood test – a sample of your blood is tested to determine whether your immune system reacts to a suspected allergen

Read more about diagnosing allergies.

Drug-induced angioedema

If you are taking a medication known to cause drug-induced angioedema, your GP will withdraw that medication and prescribe an alternative. You should not stop taking any prescribed medication without advice from a health professional.

If you don't have any further episodes of angioedema, a diagnosis of drug-induced angioedema can be made.

Hereditary angioedema

Hereditary angioedema can be diagnosed using a blood test to check the level of proteins regulated by the C1-inh gene. A very low level would suggest  hereditary angioedema.

The diagnosis and management of hereditary angioedema is highly specialised and should be carried out in a specialist immunology clinic.

Idiopathic angioedema

Idiopathic angioedema is usually confirmed by a  "diagnosis of exclusion". This means a diagnosis of idiopathic angioedema can only be made after all the above tests have been carried out and a cause has not been found. 

As angioedema can be associated with other medical problems – such as an iron deficiency, liver diseases and problems with the thyroid gland – your doctor or specialist will undertake some simple blood tests to check for these conditions.