What is severe asthma and how is it diagnosed?

Severe asthma is a type of asthma that’s hard to control with the usual asthma medicines. It’s the most serious type of asthma and needs specialist treatments.

How many people with asthma have severe asthma?

Up to 7 million people in the UK live with asthma.

Only around 4 in 100 adults with asthma have severe asthma. Severe asthma affects around 3 in 100 children with asthma too.

Is severe asthma considered a disability?

Your severe asthma may be considered a disability under the Equality Act 2010 in Scotland, England and Wales, and the Disability Discrimination Act 1995 in Northern Ireland.

This means that if you’ve been diagnosed with severe asthma, you may be able to get financial support and benefits.

You can also ask your employer for any adjustments you may need at work. Citizens Advice have more advice and support on how to do this.

If you have severe asthma you may:

• have lots of symptoms like coughing, wheezing, a tight chest and breathlessness most days
• have frequent asthma attacks which can happen without warning
• find it hard to control symptoms even with higher doses of medicines.

Having these symptoms does not always mean you have severe asthma.

If you’ve had a very bad asthma attack, it also does not mean you have severe asthma. Everyone with asthma can be at risk of having an asthma attack. It’s a sign that your asthma is not well controlled.

Difficult or hard to control asthma

Your GP may say you have ‘difficult asthma’ or ‘asthma that’s hard to control’ if in the last 12 months you:

• needed two or more courses of steroid tablets
• went to hospital or A&E at least once for your asthma
• were prescribed six blue relievers. Using your blue reliever inhaler too much can be harmful and put you more at risk of uncontrolled asthma.
• have had lots of symptoms, even with high dose treatments

OR

• have been on maintenance steroid tablets (ongoing).

There can be lots of reasons why someone’s asthma is difficult to control, like allergies, stress or other medical conditions.

Most people who have uncontrolled or ‘difficult’ asthma do not have severe asthma. Their symptoms can get better with the right treatment and support.

Type 2 inflammation

Asthma is an inflammatory condition. This means that your symptoms happen because of inflammation or swelling in your airways.

Most people with difficult to control or severe asthma have a more severe type of inflammation called Type 2 inflammation. Type 2 inflammation is linked to allergies or higher levels of a blood cell called an eosinophil.

Not taking your inhaler regularly and incorrect inhaler technique are common causes of uncontrolled Type 2 inflammation.

There are different types of severe asthma. These are known as phenotypes.

Your specialist team may say you have:

Knowing what phenotype of severe asthma you have can help you and your healthcare professionals work out what treatments will work best for you.

For example, some treatments target Type 2 inflammation which is a feature of severe eosinophilic or severe allergic asthma. 

If you have symptoms that are hard to control, see your GP. Your GP can review your asthma to see what’s causing your symptoms.

Your GP can talk to you about:

• any problems you have like forgetting to take your inhalers, or avoiding taking your medicines because of side effects
• using your inhaler the right way. The wrong inhaler technique can stop the medicine getting to your lungs.
• avoiding triggers like smoking or vaping, or triggers at work like dust or chemicals
• your mental wellbeing. Stress, anxiety and depression can all make symptoms worse.
• any allergies, including seasonal allergies like hay fever
• other conditions like obstructive sleep apnoea (OSA), obesity, acid reflux, allergies, and anxiety and depression which can all make asthma difficult to control.

If your asthma improves with support and a good medicine routine, you do not have severe asthma.

But your GP should refer you to a specialist asthma team if your symptoms are still not well controlled after a review.  Find out more about getting a referral for specialist care.

Your GP may also arrange tests like FeNO (fractional exhaled nitric oxide), spirometry or blood tests. You may have had these tests before when you were first diagnosed with asthma.

Doctors may say your asthma is difficult to control for some time before they can confirm a diagnosis of severe asthma. This is so specialists can make sure you’ve tried all the usual asthma treatments, and that other possible causes for your symptoms have been treated as well, before they can confidently diagnose severe asthma.’ Dr Andy Whittamore, GP

Your specialist care team can arrange more tests to help confirm or rule out severe asthma.

You may need to do some tests more than once. This is because results can be different depending on time of day, or if you’re taking oral steroids.  Results can sometimes be different if you smoke too.

You may have some or all of these tests to help your doctor and specialist team confirm or rule out severe asthma. Some tests can also show what type of severe asthma you have. 

Asthma Control Test

The Asthma Control Test is a set of five questions that helps your GP or specialists see how well controlled your asthma has been during the last four weeks.

FeNO (fractional exhaled nitric oxide)

If your FeNO levels go down after using your steroid preventer inhaler regularly and with good technique, you do not have severe asthma. A FeNO test may also be used to monitor some types of severe asthma.

Find out more about FeNO tests.

Blood tests

A blood test will check for signs of inflammation or allergies. It can also test for levels of a blood cell called an eosinophil. These blood cells are an important part of the immune system. But too many can cause inflammation. If your GP arranged this test, they may refer you to a respiratory specialist if the results show high levels of eosinophils.

A blood eosinophil test can also help to confirm what type of severe asthma you have, and which biologics you may be able to have.

Biologics are a specialist treatment which can help you to control your asthma symptoms better.

Find out more about biologic therapies.

Allergy blood test

If you’ve got any allergy signs or symptoms, your doctor may ask for an Immunoglobulin E (IgE) allergy blood test.

IgE is a protein in our blood. High levels of IgE protein in your blood can suggest that you’re allergic to something.

Your healthcare professional may ask you to do the test before taking your inhalers to get an accurate result. This is because the allergic response can be less if you’re taking steroid inhalers for your asthma.

Find out more about blood tests to help diagnose asthma and other lung conditions.

Spirometry and broncho-reversibility test

A spirometry test measures how much air you can breathe out in a set time. A spirometry test can be used to monitor your severe asthma too. The results can show how well your medicines are working.

A spirometry test is often done alongside a bronchodilator reversibility test (BDR).

Find out more about a spirometry and bronchodilator reversibility test and what the results mean.

Sputum test

You may be asked to provide a sample of your phlegm (sputum) so it can be tested for eosinophils. It can help your specialist team learn more about what’s causing inflammation in your airways.

CT scan

A CT scan gives more detail than a chest X-ray. It can help doctors see what might be causing your difficult asthma symptoms.

Find out more about other tests used to diagnose asthma and lung conditions.

If you’ve been diagnosed with severe asthma you’ll probably have lots of questions.

You should have the support of a specialist team. They can work with you to find the best treatment plan for you and your type of severe asthma. They can also treat any other related conditions that could be making your asthma worse.

You can also get support from other specialists in the clinic. For example, psychologists, speech and language therapists and physiotherapists.

Your specialist team can answer any questions or concerns you have about your severe asthma diagnosis and what this means.

Specialist treatments like biologics are making a big difference to many people with severe asthma.

But living with severe asthma is linked to some risks and complications and can be linked to lower life expectancy.

Risks and complications

• If you have severe asthma you’re more at risk of airway remodelling. This is when asthma inflammation over a long period of time, and asthma attacks, can cause changes in your airways. Your airways can become more narrow, scarred and inflamed.
• Some people who have had severe asthma for long time can develop COPD (chronic obstructive pulmonary disease) alongside their severe asthma. We have advice and support about COPD.

Lower life expectancy

Lower life expectancy from severe asthma is linked to getting older, poor living conditions, whether or not you smoke, and how well your symptoms are managed.

Talk to your specialist team if you have any concerns about this. They can support you to feel more confident that you’re managing your asthma as well as you can.

You can also call our Helpline.