If it is due to bacterial infection caused by rhinitis, sinusitis, washing the nose to wash out yellow snot is normal, because rinsing helps discharge nasal secretions. Under normal circumstances, the mucous glands inside the mucous membrane of the nasal cavity secretes liquid is transparent, the nasal cavity also has countless nasal cilia, through the nasal cilia constantly to the back of the nasal cavity swinging, mixed with the respiratory inhalation of the nasal cavity of the air in the dust and bacteria in the nasal mucus, to the nasopharyngeal part, by the swallowing action of swallowing into the stomach. Even if there is a small amount of snot after air drying boogers are usually gray or white. When the nasal cavity after the occurrence of bacterial infection, generally will appear yellow snot, such as viral cold combined with bacterial infection, chronic inflammation of rhinitis combined with bacterial infection, sinusitis and other diseases, flow yellow snot at the same time will also be accompanied by related symptoms of discomfort. After the discovery of yellow nasal discharge, we should actively seek medical treatment to find the cause of the disease, and give symptomatic treatment, so as to avoid delaying the condition.