<unk>  is a defense mechanism  for preventation of airway irritation or aspiration  by cleaning excessive secretion or foreign body from the airway and also it may spread infection.<unk>  is the symptom of involving organs such as upper airway tract, lung, heart, or gastrointestinal tract. Dependent on the duration of<unk> , it can be categorized to three groups including  acute, subacute, chronic. Acute<unk>  is the most common causes of seeking medical attention every year. Chronic<unk>  may affect the quality of life and also may increase mortality based on the underlying disorder. Assessment of the life threatening causes of<unk>  such as obstructive airway disease or pulmonary embolism is of important.
Cough
Sneeze
Choking
Drooling
Trench mouth
Breathe odor
Hypernea
Bronchospasm