傷風感冒及免疫力

Coughing is a reflex action of the throat to rid itself of any built up mucus or phlegm.

The word asthma comes from the Greek word for "panting". It is a chronic inflammatory disease that is accompanied by wheezing and shortness of breath. The two main types of asthma are intrinsic asthma, which usually develops in conjunction with an infection or later in life or may follow the birth of a child or after change of life, and extrinsic asthma, which is caused by allergies.

A cold is an infection of the upper respiratory tract that may be caused by a number of viruses, while influenza is a more severe viral infection with symptoms that tend to last longer and include fever.