Yellow fluid from the nose is a symptom of certain diseases, such as sinusitis, maxillary sinus mucosal cysts, nasal vestibular eczema and other diseases. 1. Sinusitis: it is an inflammatory disease of the sinus mucosa, mostly caused by bacterial, fungal or viral infections. If there is a chronic inflammatory reaction in the mucosa of the sinuses, the color of the nasal mucus will be yellow; there may also be nasal congestion, headache, decreased sense of smell and a variety of systemic symptoms. 2. Mucosal cyst of maxillary sinus: due to the blockage of mucus gland ducts in the mucosa of sinus, the mucus accumulates to form cysts. Individuals may have chronic maxillary sinus inflammation symptoms, occasional persistent dull head pain, or cheek pressure or upper teeth pain on the same side, etc. Occasionally, it may be manifested as intermittent discharge of yellow fluid from the nasal cavity. 3. Nasal vestibule eczema: allergic disease produced by the irritation of the skin of the nasal vestibule due to various reasons, which belongs to type IV allergic reaction, and it can be seen as the symptoms of broken skin of the nasal vestibule, itching, and yellowish water flowing, etc. This symptom alone is not enough to diagnose the disease. This symptom alone is not enough to diagnose the disease, and may be caused by other factors. It is recommended that the patient should consult a doctor in time to clarify the cause of the disease and give targeted treatment.