There are many reasons for coughing after a cold, such as acute tracheobronchitis, pneumonia, chronic pharyngitis and so on. 1. Acute tracheobronchitis: A prolonged cold can turn into acute tracheobronchitis, usually due to secondary bacterial infections, which can cause coughing after a cold, accompanied by coughing up yellow sputum and thick sputum. 2. Pneumonia: If a cold is prolonged, it can lead to pneumonia, which can result in coughing, accompanied by coughing up phlegm, usually due to bacterial infections. 3. Chronic pharyngitis: colds can cause pharyngeal mucosal congestion, edema, combined with chronic pharyngitis, which can lead to itchy throat, foreign body sensation, irritating cough, which leads to coughing after a cold. There are many reasons for coughing after a cold, it is recommended to go to the hospital in a timely manner to clarify the cause of the disease, under the guidance of the doctor for treatment.