How is severe asthma diagnosed?

Find out the steps to getting a diagnosis

Health advice > Severe asthma > Diagnosing severe asthma


Why severe asthma can be difficult to diagnose 

If your asthma fails to respond to the usual asthma medicines, you may be diagnosed with severe asthma.

There is not one test that can tell you if you have severe asthma. There are also different types of severe asthma. All this makes it difficult to diagnose severe asthma. 

Getting a severe asthma diagnosis usually involves: 

  • trying a range of asthma medicines at a higher dose, or a different combination, to see if they can manage your symptoms
  • checking other causes for your symptoms, and ruling them out before a diagnosis of severe asthma can be made
  • conducting further tests such as scans and blood tests to diagnose which kind of severe asthma you have. 

The signs of  severe asthma 

If you’ve been diagnosed with asthma and you’re taking all the usual asthma treatments exactly as prescribed, but your symptoms haven’t improved, your GP or asthma nurse will look for signs, including: 

  • using your reliever inhaler three or more times per week
  • a three day, or longer, course of steroid tablets for your asthma, two or more times in the past year
  • needing steroid tablets every day to control your asthma symptoms
  • your symptoms when you have an asthma attack, how often you have them, when they happen, what triggers them, and what relieves the symptoms and for how long.
  • how many A&E visits and hospital stays you have had in the past year
  • how your asthma symptoms affect your life – for example, if you’re waking at night because of your asthma, needing time off work or you’ve stopped going out as much as you used to
  • any preventer medicines you’re taking, or have taken, and if they’ve helped to control your asthma symptoms or caused side effects. 

If your GP can see that you’re taking your asthma medicines exactly as prescribed and they’re not controlling your symptoms, they can refer you to a specialist asthma clinic for a consultation. 

There may be some time between your referral and going to the specialist clinic, but your GP and asthma nurse will continue to support you in managing your asthma while you're waiting. 

Staff at a specialist asthma clinic 

If you’re referred for a specialist appointment, it will depend on the set-up at the clinic, and your own individual needs, which healthcare professionals you will see.

Your support team may include a:

  • severe asthma specialist
  • specialist asthma nurse 
  • physiotherapist
  • clinical psychologist
  • physiologist
  • pharmacist
  • dietician and/or an allergist. 

If you smoke, you may have the chance to see a smoking cessation adviser.

If your asthma means you can’t work, you may be able to talk to someone about benefits.

Your first appointment at the specialist asthma clinic 

At the first appointment your asthma consultant will want to know everything about your medical history and your lifestyle.

You’ll be asked a lot of questions about you and your asthma, many of them your GP may already have asked you. It might be frustrating to be answering them again, but the clinic specialists want to build a complete picture of you and your asthma.

Have a list of all your medicines because you’ll be asked about what you’re taking, including the doses and how you are taking them. They will also want to know about your symptoms and how your asthma affects your quality of life and the people close to you. 

This is your chance to explain what impact asthma is having on you and the people close to you. The more open and honest you can be, the better chance you’ll have of getting the right diagnosis, support and treatments.  

So, If you’re struggling to take your medicines as prescribed or you’re getting unpleasant side effects from them, let the specialist know.

Asthma care in a specialist centre

Preparing for your specialist asthma care appointment

Making your case for specialist care

Tests for severe asthma 

Along with finding out about your medical history you will also be sent for tests.

To diagnose severe asthma there are a number of tests you can take. Depending on the results, these tests can confirm you have severe asthma and the type of severe asthma it is, or show that there are other reasons for your symptoms. 

There are a lot of tests that can be used to help your doctor diagnose severe asthma, but you will probably only need some of them. 

Next steps  

You might be given different medicines or have your doses changed at your first appointment, but you will probably find out test results after the appointment. 

If you’re taking your preventer medicines correctly but your symptoms still aren’t improving, you will probably be prescribed additional medicines in various doses and combinations to see what works for you. 

You’ll be given a diagnosis of severe asthma if your healthcare professional is sure that the usual asthma medicines aren’t keeping your symptoms under control and there’s no other cause for your symptoms that can be treated or triggers that can be avoided. 

If you’re diagnosed with severe asthma, you’ll typically need treatment with a high dose of inhaled corticosteroids through an inhaler, plus a second drug such as a long-acting bronchodilator (which will usually be included in your steroid inhaler).

You may also be prescribed tablets such as leukotriene receptor antagonists (montelukast) or slow-release theophylline. Some people may also need steroid tablets to help manage their asthma.  

Eosinophilic asthma 

An estimated 40% of people with severe asthma are diagnosed with a specific type of severe asthma called eosinophilic asthma. This is asthma driven by high levels of a type of white blood cell called eosinophils. If you have high levels of eosinophils in your blood it can cause the airways to become inflamed, leading to asthma symptoms and asthma attacks. 

You're more likely to be sent for this blood test if you have other symptoms of inflammation such as eczema, sinusitis or nasal polyps. This is because eosinophilic cells can cause inflammation anywhere in your body and all through your whole respiratory system. 

If you’re diagnosed with this type of severe asthma your asthma specialist may then be able to offer you a new type of treatment called biologics, also known as monoclonal antibodies or mAbs.

These medicines have been specially designed to control the number of eosinophil cells, which will reduce the inflammation from your nose and throat down to your lungs. 

Only specialist asthma centres can treat people with biologics. Most biologics are given by injection once or twice a month.

Once you start taking a biologic therapy you’ll be monitored to see how well it works for you. If it doesn’t work well, it will be stopped, but you could be offered another biologic therapy suitable for people with severe eosinophilic asthma.

It can take time to get a severe asthma diagnosis 

Many people with severe asthma have already had asthma for some time and have tried different combinations of drugs. Just as there’s no one-off test to diagnose asthma instantly, there’s no single test to find out if the type of asthma you have is severe asthma. This means it can take time to get a diagnosis. The process and length of time will vary from person to person. 

You can call our Helpline and speak to one of our respiratory nurse specialists on 0300 222 5800 or message them via WhatsApp on 07378 606 728 (Monday-Friday, 9am-5pm) to ask any questions you have about your new diagnosis.

Last updated March 2020

Next review due June 2022

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