If you have a cough when your cold is almost over, it may be caused by a secondary bacterial infection, post-cold airway hyperresponsiveness, or cough variant asthma. 1. Secondary bacterial infection: Cold is an infectious disease of the upper respiratory tract caused by viral infection, which is generally self-limiting, and the sudden onset of coughing when the cold is almost cured may be due to a secondary bacterial infection, resulting in the reappearance of coughing symptoms. 2. Post-cold airway hyperresponsiveness: due to viral infection caused by airway hypersensitivity, so that the cough is more likely to be triggered than usual, in the cold air, odor and other stimuli, can be induced cough. In some patients, it can last for 3-8 weeks and usually improves on its own. 3. Cough variant asthma: Cough variant asthma can be triggered by colds, with symptoms such as irritating dry cough. Cough may also be caused by other reasons. If the symptoms are not relieved or aggravated, you should consult a doctor in time to clarify the cause and standardize the treatment to avoid delaying the condition.