After a cold leads to dry mouth, the reason may have the body lack of water, nasal congestion, inflammation stimulation. 1. Lack of water in the body: colds can cause a decrease in appetite, water intake is reduced, at the same time, colds and fever can lead to water evaporation and loss, which will lead to water shortages in the body, the symptoms of dry mouth and tongue. 2. Nasal congestion: Colds can cause nasal congestion, runny nose, resulting in increased inhalation of air from the mouth, open-mouth breathing can also cause dry mouth symptoms. 3. Inflammatory stimulation: colds are mostly caused by viruses and other pathogenic microorganisms, which can cause congestion and edema of the respiratory mucosa, increased secretions, oral nasopharyngeal secretions will take away some of the water, which can also cause dry mouth. Dry mouth can also be caused by other diseases, such as symptoms do not improve or aggravate, it is recommended to consult a doctor in a timely manner to clarify the cause of the disease, and take medication under the guidance of a professional doctor.