Coughing when you have a cold is mainly caused by the following reasons: a. Colds are viral infections, mostly caused by viruses felt in the upper respiratory tract. The upper respiratory tract refers to the nasopharyngeal area, which is irritated and causes congestion, edema and increased secretions in the mucous membrane of the nasopharynx, thus causing the symptoms of coughing, which is to promote the discharge of phlegm. Second, if the patient has allergic rhinitis itself, it is also easy to cause allergic pharyngitis leading to coughing. If there are a lot of secretions in the nasal cavity, backflow into the throat will also stimulate the throat and cause coughing. Many cold medicines contain chlorpheniramine maleate, which belongs to the antihistamine class and can relieve the symptoms of cough caused by cold.