Updated 25 January 2019

How is asthma diagnosed?

Learn more about the process of diagnosing asthma.

Asthma is diagnosed based on the following:

These may include coughing, wheezing, chest tightness and difficulty breathing. Note that these symptoms are also associated with other medical conditions, which is why your doctor will need more information to make an asthma diagnosis.

Medical history
Your doctor will ask questions to understand your family history, the factors that trigger your asthma symptoms, and when you tend to get asthma.

Physical examination
Your nose, mouth, throat, sinuses, ears, chest and skin will be examined. Your doctor will be looking for signs of airway narrowing, inflammation and allergic reactions. He or she will also listen to your heart and check your breathing.

Lung-function (pulmonary) tests
Your doctor will most likely test your lung function with spirometry and/or peak-flow tests.

A spirometry test checks how blocked and sensitive your airways are, and involves breathing into a mouthpiece linked to a computer. The peak-flow test also utilises a mouthpiece to check how fast you can breathe out – another indication of how well your lungs are functioning.

Allergy testing
This usually involves a skin prick test or radioallergosorben (RAST) blood test to determine what you’re allergic to. With a skin prick test, your skin will go red if exposed to a substance you’re allergic to.

Chest or sinus X-ray
A chest or sinus X-ray can help identify any structural abnormalities or diseases that may be causing your symptoms.

Reviewed by independent healthcare consultant Prof Praneet Valodia and pulmonologist Prof Elvis Irusen, Head of the Division of Pulmonology at the Faculty of Medicine and Health Sciences, Stellenbosch University. October 2018.

Read more:

- How is asthma treated?

- Asthma prevention


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Professor Keertan Dheda has received of several prestigious awards including the 2014 Oppenheimer Award, and has published over 160 peer-reviewed papers and holds 3 patents related to new TB diagnostic or infection control technologies. He serves on the editorial board of the journals PLoS One, the International Journal of Tuberculosis and Lung Disease, American Journal of Respiratory and Critical Medicine, Lancet Respiratory Diseases and Nature Scientific Reports, amongst others.Read his full biography at the University of Cape Town Lung Institute

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