Yellow snot from the throat cough spit out, this situation is generally known as postnasal drip syndrome, the cause may be acute rhinitis, sinusitis, chronic nasopharyngeal infection. 1. Acute rhinitis: patients often due to viral and bacterial infections lead to increased secretion of nasal glands, intermittent or continuous runny nose, bacterial infections are mostly yellow mucopurulent nasal mucus, nasal mucus can not be discharged from the front nostrils in a timely manner, with the movement of the cilia backflow into the pharynx, resulting in coughing up from the throat. 2. Chronic sinusitis: sinus mucosa persistent bacterial infection caused by inflammatory reaction will produce pus, pus with the surface of the nasal mucosa cilia swing or gravity flow through the nasopharynx to the throat cough. 3. Acute nasopharyngitis: acute inflammation of the mucous membrane, submucosa and lymphatic tissues of the nasopharynx, preferably in the pharyngeal tonsils. The posterior wall of the pharynx may have mucous pus flowing down from the nasopharynx. Nasopharyngeal examination: diffuse congestion and edema of the mucosa, mostly at the pharyngeal tonsils, with mucopurulent secretions attached. When yellow nasal mucus is coughed up from the throat, it is recommended to go to the hospital for a systematic examination to clarify the diagnosis and the specific cause of the disease.