Do I have asthma?

How asthma is diagnosed?


Asthma is a condition that causes your airways to become inflamed and can restrict your breathing. The symptoms typically include coughing, wheezing, tightness in the chest and breathlessness. If you experience any of these symptoms, see your GP who can diagnose whether or not you have asthma. It’s important not to ignore it as asthma is a serious condition that can become worse if it’s left untreated.


How is asthma diagnosed?

Your GP will usually be able to diagnose you based on your symptoms and a few different tests. They will discuss your symptoms and ask you how often you experience them, if anything seems to trigger them and if you have any allergies or topical conditions like eczema. They will also want to know about your family history with respiratory conditions and allergies and also lifestyle factors such as your occupational and home environment, whether or not you smoke, and how active you are.

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There are three different breathing tests that help to provide an accurate diagnosis. These are:

  • The FENO test- This tests the level of nitric oxide in your breath. A high level is a sign that your lungs are inflamed.

  • Spirometry- For this one, you blow into a machine and it calculates how much air your lungs can hold and how fast you can breathe.

  • The peak flow test- This involves blowing into a device to record how quickly you can breathe out. It’s usually done frequently over several weeks to test for accuracy.

These tests help to determine how well your lungs function and what type of treatment might be best for you. Asthma symptoms can vary over time due to different triggers so it’s not always a straightforward process to get a diagnosis. For example, breathlessness can also occur in individuals with heart conditions or as a result of a panic attack.


Peak Flow Test

The purpose of the peak flow test is to test the function of your lungs and how well you can breathe out. Your GP will get you to do this test and you may be given the device to take home so that you can measure your peak flow over time. In this case, you’ll need to keep a diary of the results so that you can get an accurate diagnosis.


How does it work?

The device resembles a small plastic tube. You hold it in your hand and take a deep breath. Then blow into the tube as hard as you can into the peak flow meter. It’s measured in litres per minute and the result is called your peak flow. It’s likely that your GP will get you to do this several times to record your personal best. This will be used in future tests to measure against, for instance, to determine if your asthma has got worse or not. The test also helps to record what your peak flow is like at different times of the day.



Spirometry tests the function of your lungs by measuring how much air you can breathe out. This is usually the first test you’ll do with your GP after discussing your symptoms. You’ll usually do one before and after taking reliever medicine to see the difference in your lungs.


How does it work?

For this test, you’ll breathe into a machine called a spirometer. Your GP will get you to start by taking a relaxed breath in and out. Then you’ll take a deep breath in and breathe out into the mouthpiece as fast as possible. It’s likely that you’ll have to do this a few times so that the doctor can record the result accurately.

Next, your GP might give you some medicine to take through a spacer to help open and relax your airways. After 15-20 minutes you’ll take the test again to see how well you can breathe after taking the medication. If there’s a significant change in the result indicating that your airways are less narrow then this makes it likely that you do have asthma.



This tests the level of nitric oxide in your breath. Nitric oxide occurs in your lungs when your airways have become inflamed, caused by something you are allergic to. If there is a high level of it in your breath then this is likely to be a sign of inflamed airways. The FENO test is used to determine whether or not you have allergic asthma.


How does it work?

You can usually do this test with your GP if they have the equipment available. If not, then you’ll be referred for a hospital outpatient appointment. For the test itself, you breathe into a tube that is attached to a monitor to show the result. All you have to do is take a deep breath in and then breathe out slowly into the tube.

You probably won’t be asked to do the FENO test at first unless your doctor thinks it’s likely your asthma is being triggered by an allergy. It is often used to determine the effectiveness of your asthma treatment during review appointments.


What happens after being diagnosed with asthma?

The first thing your doctor will do after diagnosing you with asthma is to develop a written asthma action plan with you. This will give you all the tools you need to manage your asthma and prevent attacks. It will guide you on what your medications are and how to take them, signs that your asthma is getting worse and what to do if that happens. It also explains what happens during an asthma attack. You should try and keep a copy of it with you at all times and share it with friends, family and co-workers so that they know what to do if you experience an asthma attack.

You’ll be given an inhaler to manage your asthma symptoms. Depending on how mild or severe your asthma is, you might be given more than one type. The blue reliever inhaler (such as a Ventolin Evohaler or Salamol Easi-Breathe) is given to everyone with asthma. This is for instant relief when you feel symptoms come on. If you are using this three times a week or more then you’ll also be prescribed a preventer inhaler. This is for daily use to stop symptoms from occurring.

People with severe asthma might be given additional types of medication as inhalers might not be enough to treat your condition effectively. In this case, you’ll be referred to a respiratory specialist to work out the most suitable combination of treatments for you.

Always follow the instructions provided by your doctor to make sure you are taking your inhaler medication correctly. Asthma affects everyone differently so your personal action plan should be your point of reference for managing your symptoms. If you feel unsure about anything then ask your doctor for advice.

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