The wheeze of asthma is caused by contraction of the muscular walls of the small breathing tubes in the lung. The narrowed air tube creates a 'turbulent' air flow and therefore causes a wheeze, or whistle, when the asthmatic breathes. Because the tubes into the lung are narrowed, less air can get in and this decreases the oxygen supply to the body. The muscular contraction of the breathing tubes can be stimulated by a wide range of substances such as inhaled dust or pollen, and various foods.

Acupuncture causes the contracted muscular walls to dilate; the mechanism of this is unknown, but there is good Western research data to support this claim. A recent Chinese clinical trial on asthma showed that some 70 per cent of asthmatics gained a 'good effect' from a course of acupuncture and moxibustion (about ten treatments) once a year. The acupuncture treatment was able to decrease the frequency and intensity of asthmatic attacks over a period of a year. This result is encouraging as it shows that acupuncture and moxibustion can affect the response of the body to the environmental stimuli causing asthmatic attacks.