Updated 04 September 2018

What is asthma?

Asthma is a respiratory condition that causes the airways in the body to constrict, limiting the amount of air coming in and out of the lungs.


Asthma is a common condition that entails struggling to breathe due to constricted airways. It’s the most common chronic childhood disease.

“Asthma" comes from the ancient Greek word meaning "panting", and, if you've experienced an asthma attack, you'll understand why. For some, an asthma attack feels as though an elephant is sitting on their chest, while for others breathing becomes so laboured that it’s "like trying to suck peanut butter through a straw".

It makes your chest feel tight. However, the real problem is not that you can’t breathe in properly, but that you can’t breathe out. If you can’t breathe out, no fresh air can get in.

Chronic disease

The reason why you struggle to breathe is because asthma affects the breathing pipes or tubes, called airways or bronchi. When you breathe in, oxygen-rich air flows through the airways into the alveoli, where the oxygen is passed from to the blood vessels, and carbon dioxide moves from the blood vessels to the alveoli. Carbon dioxide is breathed out. Asthma is a condition where the airways become narrow, restricting the amount of air that can flow from the alveoli.

Although asthma is a lung disease and is a long-term (chronic) disease, in which the flow of air out of the lungs is limited by obstruction, this obstruction is reversible – unlike chronic bronchitis and emphysema – as it initially does not affect the actual structure of the airways.

Asthma often develops in childhood or during the teens. People with other lung diseases, such as chronic obstructive pulmonary disease (COPD) can also develop asthma. Although it’s not clear exactly what causes asthma, it’s thought to be triggered by an allergy, or when the lungs are irritated by something in the air.

Asthmatics should be able to lead completely normal lives. This means that they should be able to live, play and sleep normally. If this is not the case, the diagnosis, treatment and medication should be re-evaluated.

Unfortunately, this condition often goes undiagnosed and untreated, as many people don't even know they're asthma sufferers. And in many cases, the condition is not managed adequately by the doctor, leaving it up to the patient.


Asthma affects one in ten children (10%) and one in twenty adults (5%). It usually begins before the age of five and is one of the most common respiratory diseases in the world today. The Global Initiative for Asthma (GINA 2015) maintains that more than 300 million people are affected by asthma worldwide.

Asthma is more common in boys and is seen predominantly in children who are allergic or come from allergic families. It tends to run in families, as do related allergic conditions, such as hay fever and eczema.

Approximately 50% of childhood asthma, particularly if it’s mild, goes into remission during the teenage years, but don’t be fooled into thinking this means you have "outgrown" asthma. About 30% of “teenagers-in-asthma-remission” redevelop asthma during adulthood. Asthma usually persists if it starts during adulthood.

Reviewed and updated by Prof Eugene Weinberg, Paediatrician Health24. April 2015

Image credit: iStock


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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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