Diagnosing angioedema is relatively straightforward, but tests are required to determine which type it is.

An examination of the affected skin by a doctor is usually enough to diagnose angioedema. You may also be asked about any associated symptoms, such as swelling of your throat or abdominal (tummy) pain.

Each type of angioedema requires different testing before it is diagnosed. These are detailed below.

Allergic angioedema

Your GP will ask whether you have recently been exposed to any common allergens (allergy-causing substances), such as nuts or latex. They will also ask whether you have a history of other allergic conditions, such as hives or asthma. People who have one allergic condition often develop other allergic conditions.

You will need to tell your doctor about all the medications that you are taking, including over-the-counter medication such as painkillers, herbal supplements and vitamins.

If you are having frequent episodes of angioedema, your GP may recommend that you keep a diary of your exposure to possible irritants.

If a diagnosis of 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 that is known to cause drug-induced angioedema, your GP will withdraw that medication and prescribe an alternative. 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 by using a blood test to check the level of proteins that are regulated by the C1-INH gene. A very low level would suggest a diagnosis of hereditary angioedema.

You may also be asked if you have a family history of 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 process known as 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 deficiency of iron, liver diseases, and problems with the thyroid gland, your doctor or specialist will undertake some simple blood tests to check for these conditions.