Asthma: Causes and risk factors

80% of asthmas in children and 50% of those in adults are caused by allergies.


Lifestyle, specifically the tendency to live in poorly ventilated areas, promotes the emergence of micro-organisms susceptible to increasing allergies that form the basis of asthmas.

The main factors that trigger asthma are: 

- Allergens: dust mites, moisture, cockroaches, pollen, animal hairs (especially cats), see food allergens 

- Smoking: occasional passive smoking from parents who smoke increases the risk of children developing asthma 

- Pollutants: combustion products (car pollution), household pollutants (solvents and volatile organic compounds, paint etc.) or industrial products (chimney smoke) 

- Gastroesophageal reflux: abnormal acid reflux from the stomach through the oesophagus can increase the risks of bronchial hyperactivity, which causes coughing or asthma attacks 

- Hormonal factors: some women experience more asthma attacks in the run up to their period. Premenstrual asthma leads to an increase in the severity of the symptoms 

- Stress or strong emotions can trigger attacks. Breathing rate can increase, causing the bronchi to contract. Stress also affects the nervous control of the bronchial tubes or the immune response to infections 

- Changes in weather conditions such as cold air or fog 

- Respiratory infections: children with asthma are sensitive to infections of the airways. Asthma most often develops for the first time following repeat cases of bronchitis 

- Flare-ups of allergic rhinitis (continuous nasal discharge and repeated sneezing), also known as “hay fever”, can trigger attacks 

These factors can have varying effects even in the same person, depending on the stage of their asthma. That said, not all allergies are asthma-related.

Last updated: 11/03/2019

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