The symptoms of asthma are different for each patient and can vary greatly even for the same patient depending on the degree of the attack. The main symptom features are as follows: (a) Repeated, sudden attacks of wheezing, chest tightness, coughing and coughing up white mucus sputum. Some patients can hear a distinct croup, a breath sound similar to whistling when breathing, during the attacks. (b) The attacks of symptoms are mostly caused by exposure to allergens, inhalation of paints, insecticides, fumes or cold air irritation, and the attacks of asthma in children are often associated with respiratory viral infections. (iii) The symptoms of asthma are sometimes diverse. Some asthma patients do not have wheezing symptoms but simply have recurrent paroxysmal cough as the main symptom, and a few patients simply show paroxysmal chest tightness and breath-holding symptoms. (iv) Some patients with asthma have allergic rhinitis. The onset of allergic rhinitis is often the precursor of an asthma attack, with symptoms including more frequent nasal congestion, sneezing, runny nose, itchy nose and itchy throat, etc. The presence of these symptoms suggests that the patient may have an asthma attack and should be given prompt treatment. (E) Cough variant asthma: Asthma in children can have no wheezing symptoms, but only a recurrent and chronic cough, called cough variant asthma. It often attacks at night and early in the morning, and exercise can aggravate the cough. Some children eventually develop classic asthma.