Diagnosing Asthma

Asthma is a clinical diagnosis. In other words, the symptoms and clinical findings are used to diagnose the condition. If you suspect that you or your child are suffering from asthma, your doctor will be able to give you a diagnosis based on your medical and family history, a physical exam, and test results.

Your doctor will also be able to tell you the severity of your asthma. The level of severity – whether it's intermittent, mild, moderate, or severe – determines the treatment options that best suit your condition.

Personal and medical history

Your doctor may ask about your family history of allergies and asthma. He or she may also ask whether you have asthma symptoms and how and when they occur.

A typical patient history might include:

  • symptoms that come and go, usually worse at night
  • cough
  • wheezing
  • difficulty breathing
  • symptoms triggered by specific items or events such as exercise, cold air or allergen exposure.
  • a personal or family history of asthma, allergic rhinitis and/or eczema
Breathing tests

Your doctor will conduct a lung function test called spirometry to assess how well your lungs are working. This is a simple blowing test that will measure how much air you inhale; how much you exhale and how quickly you can blow the air out of your lungs.

Your doctor may ask you to repeat the spirometry test after being given a medication (inhaled or nebulised) which may open the airways. The aim of this is to see if your airways open wider with medication and your lung function improves.

If the results improve, it will help confirm that you have asthma.

However, you can still have asthma with normal lung function! Which is why you need a doctor to confirm the diagnosis.

Physical examination

Your doctor will listen to your breathing and look for signs of asthma or allergies. These signs include wheezing, a runny nose or swollen nasal passages, and allergic skin conditions (such as eczema). It is important to note that you can still have asthma even if these signs do not show on the day of the physical examination.

Your doctor may recommend other tests if he or she needs more information to make a diagnosis. Other tests may include:

  • Bronchoprovocation, a test which uses spirometry to measure how sensitive your airways are to common asthma triggers.
  • Electrocardiogram (EKG) or chest x ray which examine whether another disease or foreign object may be causing your symptoms.
  • Vocal cord dysfunction, reflux disease, or sleep apnea tests to find out whether you have another condition with the same symptoms as asthma.
  • Allergy testing to identify allergens that may be affecting you.