The understanding about this disease between west and east is quite different. Here are the brief introductions from the perspectives of both west medicine and Traditional Chinese Medicine (TCM).

1. DEFINE ASTHMA AND ALLERGIES IN WESTERN VIEWPOINT
Currently it is widely believed that Bronchial Asthma is induced by environmental and host (genetic) factors. Genetics present well in many patients suffering from asthma attack by a higher risk in their relatives as well. Actually survey data has shown that others with biological ties are much easier to be attacked. Most of them, often accompanied with Allergic Rhinitis and Atopic Dermatitis, are allergic to some certain medicine, common airborne allergens like mites, pollens, pets, molds, and some certain foods like nuts, milk, peanut, and seafood, etc. Unfortunately, tell you the facts that up to this day the causes still remain not fully known. However, some have been proven are allergic reaction, chronic airway allergic inflammation (AAI), airway hyperresponsiveness (AHR) or Bronchial hyperresponsiveness (BHR), disorder of nervous regulation in the airway, epigenetic mechanism, respiratory syncytial virus, neural signal transduction mechanisms, and airway remodeling and the interactions, etc.

2. UNDERSTAND WHAT CAUSES ASTHMA FROM TCM
The name of Xiao Chuan was initially introduced in Dan Xi Xin Fa (Zhu Danxi's Central Methods, literally, "heart" methods). But similar terms describing the symptoms, like abnormal rising of Qi and gasp, were way earlier in Huangdi Neijing (The Inner Canon of Huangdi). Chinese medicine believes that the root cause lies in deficiency combined with underlying chronic phlegm in lung. On top of exogenous pathogenic attacks, eating disorders, disorders in minds and emotions, and overstrains causing internal damage, it will lead to retention of phlegm in airway and adverse rising of lung Qi, which in turn induce these symptoms and signs. Clinically it divides into the attack stage and chronic remission stage (symptom-free for very long periods), in which different herbs for asthma should be used respectively.