Sudden coughing occurs for a number of reasons: First, it is likely to be caused by smelling an irritating gas that causes spasm of the bronchial smooth muscle, resulting in the onset of coughing, which can often be gradually relieved by getting out of a bad environment. Second, exposure to an allergen has induced an allergic cough. In this case, you need to get rid of the allergen and take anti-allergy medication for allergic cough, such as loratadine, desloratadine or cetirizine hydrochloride. Third, you may have inhaled a foreign body and need to go to the hospital to have it treated by a doctor. However, if the foreign body is deeper, it still needs to be treated by a doctor. 4. It may be cough variant asthma, which often requires long-term anti-asthma treatment, such as long-term inhalation of Symbicort to relieve cough symptoms, or chewing a chewable tablet of montelukast sodium before bedtime to prevent sudden coughing.