ASTHMA: Causes, incidence and risk factors (more detail)
Asthma caused by inflammation of the airways. When the asthma attack occurs, the muscles surrounding the airways become tight and the lining of the air passages swell. This will reduce the amount of air that can pass, and can lead to wheezing sounds.
Most people with asthma have wheezing attacks separated by symptom-free period. Some patients have long-term shortness of breath more and more episodes of breathlessness. However, on the other, cough in may the main symptoms. Asthma attacks can last minutes to days and can become dangerous if the airflow is severely limited.
In sensitive individuals, asthma symptoms can be triggered by respiratory allergy causing substances (called allergens or triggers). Triggering including animal dander, dust mites, cockroach allergens, molds, or pollens. Symptoms of asthma can be triggered by respiratory infections, exercise, cold air, tobacco smoke and pollution, stress, diet, or drug allergy. Aspirin and non-steroidal anti-inflammatory drugs (NSAIDs) to cause asthma in some patients.
Many people with asthma or a person has a family history of allergies such as hay fever (allergic rhinitis) or eczema. Others have no history of allergy.
