When a parent hears that their child has asthma or an adult is diagnosed with this condition, they may wonder what causes asthma. There are three dimensions to the causes of asthma: personal history, family history, and environmental triggers. The causes of asthma can be considered risk factors of asthma since not everyone who has these risk factors will develop asthma.

The patient’s family history can predispose someone to developing asthma. If a person’s parents have asthma, the patient is more likely to develop asthma. The genetic component to asthma is a predisposition to allergies which is caused by an immune system that is sensitive to allergens. The family history does not have to be strictly one of asthma to make an individual prone to asthma. Eczema, allergies, and asthma are all conditions that are related to an oversensitive immune system. This inherited condition of a sensitive immune system is called atopy.

If a child has had a history of respiratory infections, the child is at greater risk for developing asthma. Some children who have asthma seemed to have had frequent respiratory infections or croup in infancy and early childhood. It’s hard to say if these infections made the child more susceptible to asthma or if the infections were merely signs that the susceptibility of asthma already existed. It is thought that some previous viral infections may affect an infant’s or child’s developing immune system and trigger the onset of asthma.

Environmental factors can affect the development and flare-ups of asthma. Some adults develop asthma after working around toxins. Allergens in the environment may also aggravate the condition and cause the onset of asthma symptoms. Common allergens such as dust mites, pet dander, or cigarette smoke can exacerbate the condition. If someone has an inherited tendency to asthma and is exposed to environmental allergens, it may increase the sensitivity of the individual’s immune system to inhaled substances.

It is not clear why some people may have all these risk factors and not develop asthma, while others may have one risk factor and develop this condition. However, an individual who has these risk factors is at significantly higher risk of developing asthma than someone who does not.

One may think that a child who does not have viral or respiratory infections and is not exposed to environmental allergens may be safe from developing asthma. However, some people believe that a lack of exposure to these things robs the immune system of learning to react appropriately to substances and may in fact increase the risk of developing asthma and allergies. This is one of the concepts behind warnings against overuse of anti-bacterial products.