A child with a cold cough consider the normal manifestation of colds, but also consider and child allergies, mycoplasma infections and other factors have a relationship. 1. Cold performance: cold is a viral upper respiratory tract infection, pathogens invade the mucous membrane of the nasopharynx, resulting in local mucosal congestion and edema, as well as mucus exudation, which causes dry, itchy and painful throat, cough and phlegm and other symptoms. 2. Allergic factors: a part of the children belong to the allergic body, every time after the cold due to viral infection, the virus violates the respiratory mucosa, and induces the airway hyperreactivity, thus coughing. 3. Mycoplasma infection: some children with low immunity, after a cold will be combined with bacterial, mycoplasma or other pathogenic bacterial infections, combined with mycoplasma infections tend to show frequent coughing, longer duration of the disease, and easy to repeat. Coughing when a child has a cold may also have other reasons, it is recommended to go to the hospital in time to improve the examination to clarify the cause of the disease, to give targeted treatment or treatment.