Diagnosis

Asthma can usually be diagnosed from your symptoms and some simple tests.

Your GP will probably be able to diagnose it, but they may refer you to a specialist if they're not sure.

Seeing your GP

Your GP may ask:

  • what symptoms you have
  • when they happen and how often
  • if anything seems to trigger them
  • if you have conditions such as eczema or allergies, or a family history of them

They may suggest doing some tests to confirm if you have asthma.

These can't always be done easily in young children, so your child may be given an asthma inhaler to see if it helps relieve their symptoms until they're old enough to have the tests.

Tests for asthma

The main tests used to help diagnose asthma are:

  • FeNO test – you breathe into a machine that measures the level of nitric oxide in your breath, which is a sign of inflammation in your lungs
  • spirometry – you blow into a machine that measures how fast you can breathe out and how much air you can hold in your lungs
  • peak flow test – you blow into a handheld device that measures how fast you can breathe out, and this may be done several times over a few weeks to see if it changes over time

After you're diagnosed with asthma, you may also have allergy tests to see if your symptoms might be triggered by an allergy.

Asthma UK has more information on diagnosing asthma.

Page last reviewed: 19/02/2018
Next review due: 19/02/2021